Zoom lens, optical apparatus, and method for manufacturing zoom lens

ABSTRACT

A zoom lens includes, in order from an object along an optical axis: a first lens group having a negative refractive power; a second lens group having a positive refractive power; a third lens group having a negative refractive power; a fourth lens group; and a fifth lens group. When the zoom lens performs varying magnification, the distance between the first and second lens groups changes, the distance between the second and third lens groups changes, the distance between the third and fourth lens groups changes, the distance between the fourth and fifth lens groups changes, the second and fourth lens groups move along the same trajectory along the optical axis, and at least the third lens group moves along the optical axis.

TECHNICAL FIELD

The present invention relates to a zoom lens, an optical apparatus, anda method for manufacturing a zoom lens which are ideal for photographiccameras, electronic still cameras, video cameras, and the like.

Priority is claimed on Japanese Patent Application No. 2015-017212,filed Jan. 30, 2015, the content of which is incorporated herein byreference.

TECHNICAL BACKGROUND

Conventionally, a vibration-reduction (variable power optical system)having a wide angle of view has been proposed (for example, see PatentDocument 1).

RELATED ART DOCUMENTS Patent Document

Patent Document 1:

-   Japanese Patent Application, Publication No. 2007-279077

SUMMARY OF INVENTION Technical Problem

However, there is a problem that the conventional vibration-reductiondescribed above cannot sufficiently meet the demands for optical systemshaving an F-number for brightness and an excellent optical performance.

Solution to Problem

According to an aspect of the present invention, there is provided azoom lens including, in order from an object along an optical axis, afirst lens group having a negative refractive power, a second lens grouphaving a positive refractive power, a third lens group having a negativerefractive power, a fourth lens group, and a fifth lens group, whereinwhen the zoom lens performs varying magnification, the distance betweenthe first and second lens groups changes, the distance between thesecond and third lens groups changes, the distance between the third andfourth lens groups changes, the distance between the fourth and fifthlens groups changes, the second and fourth lens groups move along thesame trajectory along the optical axis, and at least the third lensgroup moves along the optical axis. In an example, the fourth lens groupmay have a positive refractive power and the fifth lens group may have apositive refractive power.

According to another aspect of the present invention, there is provideda zoom lens including, in order from an object along an optical axis: afirst lens group having a negative refractive power, a second lens grouphaving a positive refractive power, a third lens group having a negativerefractive power, a fourth lens group having a positive refractivepower, and a fifth lens group having a positive refractive power,wherein when the zoom lens performs varying magnification from awide-angle end state to a telephoto end state, the second and fourthlens groups move by the same distance along the optical axis, and atleast the third lens group moves along the optical axis.

According to another aspect of the present invention, there is provideda method for manufacturing a zoom lens, wherein the zoom lens includes,in order from an object along an optical axis: a first lens group havinga negative refractive power, a second lens group having a positiverefractive power, a third lens group having a negative refractive power,a fourth lens group, and a fifth lens group, wherein the methodincludes: arranging the zoom lens such that, when the zoom lens performsvarying magnification, the distance between the first and second lensgroups changes, the distance between the second and third lens groupschanges, the distance between the third and fourth lens groups changes,the distance between the fourth and fifth lens groups changes, thesecond and fourth lens groups move along the same trajectory along theoptical axis, and at least the third lens group moves along the opticalaxis. In an example, the fourth lens group may have a positiverefractive power and the fifth lens group may have a positive refractivepower.

According to another aspect of the present invention, there is provideda method for manufacturing a zoom lens, wherein the zoom lens includes,in order from an object along an optical axis: a first lens group havinga negative refractive power, a second lens group having a positiverefractive power, a third lens group having a negative refractive power,a fourth lens group having a positive refractive power, and a fifth lensgroup having a positive refractive power, wherein the method includes:arranging the zoom lens such that, when the zoom lens performs varyingmagnification from a wide-angle end state to a telephoto end state, thesecond and fourth lens groups move by the same distance along theoptical axis, and at least the third lens group moves along the opticalaxis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a zoom lens according to Example 1,wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 2 shows graphs illustrating various aberrations of the zoom lensaccording to Example 1 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 3 shows graphs illustrating various aberrations of the zoom lensaccording to Example 1 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 4 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 1 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 5 is a are cross-sectional view of a zoom lens according to Example2, wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 6 shows graphs illustrating various aberrations of the zoom lensaccording to Example 2 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 7 shows graphs illustrating various aberrations of the zoom lensaccording to Example 2 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 8 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 2 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 9 is a cross-sectional view of a zoom lens according to Example 3,wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 10 shows graphs illustrating various aberrations of the zoom lensaccording to Example 3 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 11 shows graphs illustrating various aberrations of the zoom lensaccording to Example 3 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 12 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 3 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 13 is a cross-sectional view of a zoom lens according to Example 4,wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 14 shows graphs illustrating various aberrations of the zoom lensaccording to Example 4 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 15 shows graphs illustrating various aberrations of the zoom lensaccording to Example 4 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 16 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 4 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 17 is a cross-sectional views of a zoom lens according to Example5, wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 18 shows graphs illustrating various aberrations of the zoom lensaccording to Example 5 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 19 shows graphs illustrating various aberrations of the zoom lensaccording to Example 5 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 20 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 5 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 21 is a cross-sectional views of a zoom lens according to Example6, wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 22 shows graphs illustrating various aberrations of the zoom lensaccording to Example 6 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 23 shows graphs illustrating various aberrations of the zoom lensaccording to Example 6 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 24 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 6 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 25 is a cross-sectional view of a zoom lens according to Example 7,wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 26 shows graphs illustrating various aberrations of the zoom lensaccording to Example 7 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 27 shows graphs illustrating various aberrations of the zoom lensaccording to Example 7 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 28 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 7 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 29 is a cross-sectional view of a zoom lens according to Example 8,wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 30 shows graphs illustrating various aberrations of the zoom lensaccording to Example 8 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 31 shows graphs illustrating various aberrations of the zoom lensaccording to Example 8 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 32 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 8 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 33 is a cross-sectional view of a zoom lens according to Example 9,wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 34 shows graphs illustrating various aberrations of the zoom lensaccording to Example 9 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 35 shows graphs illustrating various aberrations of the zoom lensaccording to Example 9 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 36 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 9 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 37 is a cross-sectional views of a zoom lens according to Example10, wherein parts (a), (b), and (c) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 38 shows graphs illustrating various aberrations of the zoom lensaccording to Example 10 upon focusing on an object at infinity, whereinparts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 39 shows graphs illustrating various aberrations of the zoom lensaccording to Example 10 upon focusing on an object at a close point,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 40 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 10 when vibration reduction is performed,wherein parts (a), (b), and (c) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 41 is a schematic diagram illustrating a configuration of a camerahaving a zoom lens.

FIG. 42 is a diagram illustrating an outline of a method formanufacturing a zoom lens.

FIG. 43 is a diagram illustrating an outline of a method formanufacturing a zoom lens.

DESCRIPTION OF EMBODIMENTS

An embodiment of a zoom lens, an optical apparatus, and a zoom lensmanufacturing method will now be described. First, a zoom lens accordingto an embodiment will be described.

There is provided a zoom lens including, in order from an object alongan optical axis, a first lens group having a negative refractive power,a second lens group having a positive refractive power, a third lensgroup having a negative refractive power, a fourth lens group, and afifth lens, wherein when the zoom lens performs varying magnification,the distance between the first and second lens groups changes, thedistance between the second and third lens groups changes, the distancebetween the third and fourth lens groups changes, the distance betweenthe fourth and fifth lens groups changes, the second and fourth lensgroups move along the same trajectory along the optical axis, and atleast the third lens group moves along the optical axis. In an example,the fourth lens group may have a positive refractive power and the fifthlens group may have a positive refractive power.

Alternatively, there is provided a zoom lens including, in order from anobject along an optical axis, a first lens group having a negativerefractive power, a second lens group having a positive refractivepower, a third lens group having a negative refractive power, a fourthlens group having a positive refractive power, and a fifth lens grouphaving a positive refractive power, wherein when the zoom lens performsvarying magnification (varying power) from a wide-angle end state to atelephoto end state, the second and fourth lens groups move by the samedistance along the optical axis, and at least the third lens group movesalong the optical axis.

Due to this configuration, it is possible to perform varyingmagnification and to correct aberrations satisfactorily upon varyingmagnification.

Moreover, it is preferable that the zoom lens satisfy ConditionalExpression (1) below.1.500<(−f3)/fw<10.000  (1)

where

f3: a focal length of the third lens group

fw: a focal length of the entire zoom lens system in the wide-angle endstate

Conditional Expression (1) is a conditional expression for defining anappropriate range of the ratio of the focal length of the third lensgroup with respect to the focal length of an entire system of the zoomlens in the wide-angle end state. When Conditional Expression (1) issatisfied, it is possible to realize a brightness of an F-number ofapproximately F2.8 to F4.0 and to correct various aberrations includingspherical aberration satisfactorily.

When a correspondence value of Conditional Expression (1) exceeds theupper limit value, the burden of coma aberration correction by thefourth lens group increases, eccentricity sensitivity of the fourth lensgroup increases, and it may be difficult to correct coma aberration. Asa result, it may be difficult to realize a brightness of an F-number ofapproximately F2.8 to F4.0. In order to obtain the effect reliably, itis preferable that the upper limit value of Conditional Expression (1)be set to 8.500. Moreover, in order to obtain the effect more reliably,it is preferable that the upper limit value of Conditional Expression(1) be set to 7.000.

On the other hand, when the correspondence value of ConditionalExpression (1) is smaller than the lower limit value, the burden ofvarying magnification on lens groups other than the third lens groupincreases. The eccentricity sensitivity of the second and fourth lensgroups particularly increases, and it may be difficult to correctspherical aberration and coma aberration. As a result, it may bedifficult to realize a brightness of an F-number of approximately F2.8to F4.0. In order to obtain the effect reliably, it is preferable thatthe lower limit value of Conditional Expression (1) be set to 1.800.Moreover, in order to obtain the effect more reliably, it is preferablethat the lower limit value of Conditional Expression (1) be set to2.100.

Moreover, it is preferable that the zoom lens satisfy ConditionalExpression (2) below.0.050<|m34|/fw<1.500  (2)

where

|m34|: a change from the wide-angle end state to the telephoto endstate, in terms of the distance on the optical axis from the lenssurface closest to image, of the third lens group to the lens surfaceclosest to object, of the fourth lens group

fw: a focal length of an entire system of the zoom lens in thewide-angle end state

Conditional Expression (2) relates to the varying magnification burdenof the third and fourth lens groups and is a conditional expression fordefining an appropriate range of the ratio of a change from thewide-angle end state to the telephoto end state, in terms of thedistance on the optical axis from the lens surface closest to image, ofthe third lens group to the lens surface closest to object, of thefourth lens group with respect to the focal length of an entire systemof the zoom lens in the wide-angle end state.

When the correspondence value of Conditional Expression (2) exceeds theupper limit value, the distance between the fourth lens group and theimage plane is decreased, the burden of curvature of field correction bythe fourth lens group increases, and it may be difficult to correct comaaberration and curvature of field. In order to obtain the effectreliably, it is preferable that the upper limit value of ConditionalExpression (2) be set to 1.250. Moreover, in order to obtain the effectmore reliably, it is preferable that the upper limit value ofConditional Expression (2) be set to 1.000.

On the other hand, when the correspondence value of ConditionalExpression (2) is smaller than the lower limit value, the varyingmagnification burden of lens groups other than the fourth lens groupincreases, and the power of the second lens group particularly isincreased, and it may be difficult to correct spherical aberration andcoma aberration. In order to obtain the effect reliably, it ispreferable that the lower limit value of Conditional Expression (2) beset to 0.090. Moreover, in order to obtain the effect more reliably, itis preferable that the lower limit value of Conditional Expression (2)be set to 0.130.

Moreover, it is preferable that the zoom lens satisfy ConditionalExpression (3) below.1.000<f5/(−f1)<10.000  (3)

where

f5: a focal length of the fifth lens group

f1: a focal length of the first lens group

Conditional Expression (3) is a conditional expression for defining anappropriate range of the ratio of the focal length of the fifth lensgroup with respect to the focal length of the first lens group. WhenConditional Expression (3) is satisfied, it is possible to realize abrightness of an F-number of approximately F2.8 to F4.0 and a wide angleof view and to correct various aberrations including sphericalaberration satisfactorily.

When the correspondence value of Conditional Expression (3) exceeds theupper limit value, the power of the first lens group with respect to thefifth lens group is increased and it may be difficult to correctcurvature of field and curvature aberration in the wide-angle end stateparticularly. In order to obtain the effect reliably, it is preferablethat the upper limit value of Conditional Expression (3) be set to8.700. Moreover, in order to obtain the effect more reliably, it ispreferable that the upper limit value of Conditional Expression (3) beset to 7.400.

On the other hand, when the correspondence value of ConditionalExpression (3) is smaller than the lower limit value, the power of thefifth lens group with respect to the first lens group is increased andit may be difficult to correct curvature of field and curvatureaberration in the telephoto end state particularly. In order to obtainthe effect reliably, it is preferable that the lower limit value ofConditional Expression (3) be set to 1.700. Moreover, in order to obtainthe effect more reliably, it is preferable that the lower limit value ofConditional Expression (3) be set to 2.400.

Moreover, it is preferable that the zoom lens satisfy ConditionalExpression (4) below.0.300<|m12|/fw<5.000  (4)

where

|m12|: a change from the wide-angle end state to the telephoto endstate, in terms of the distance on the optical axis from the lenssurface closest to image, of the first lens group to the lens surfaceclosest to object, of the second lens group

fw: a focal length of an entire system of the zoom lens in thewide-angle end state

Conditional Expression (4) relates to the varying magnification burdenof the first and second lens groups and is a conditional expression fordefining an appropriate range of the ratio of the change from thewide-angle end state to the telephoto end state, in terms of thedistance on the optical axis from the lens surface closest to image, ofthe first lens group to the lens surface closest to object, of thesecond lens group with respect to the focal length of an entire systemof the zoom lens in the wide-angle end state.

When the correspondence value of Conditional Expression (4) exceeds theupper limit value, the distance between the first lens group and theimage plane is increased, the burden of spherical and coma aberrationcorrection by the second lens group increases, and it may be difficultto correct spherical and coma aberration. In order to obtain the effectreliably, it is preferable that the upper limit value of ConditionalExpression (4) be set to 4.000. Moreover, in order to obtain the effectmore reliably, it is preferable that the upper limit value ofConditional Expression (4) be set to 3.000.

On the other hand, when the correspondence value of ConditionalExpression (4) is smaller than the lower limit value, the varyingmagnification burden of lens groups other than the first lens groupincreases, and the power of the fourth lens group particularly isincreased, and it may be difficult to correct coma aberration. In orderto obtain the effect reliably, it is preferable that the lower limitvalue of Conditional Expression (4) be set to 0.600. Moreover, in orderto obtain the effect more reliably, it is preferable that the lowerlimit value of Conditional Expression (4) be set to 0.900.

Moreover, it is preferable that the zoom lens satisfy ConditionalExpression (5) below.0.200<f5/f4<4.000  (5)

where

f5: a focal length of the fifth lens group

f4: a focal length of the fourth lens group

Conditional Expression (5) is a conditional expression for defining anappropriate range of the ratio of the focal length of the fifth lensgroup with respect to the focal length of the fourth lens group. Whenthe correspondence value of Conditional Expression (5) exceeds the upperlimit value, the power of the fourth lens group with respect to thefifth lens group is increased and it may be difficult to correct comaaberration. In order to obtain the effect reliably, it is preferablethat the upper limit value of Conditional Expression (5) be set to3.300. Moreover, in order to obtain the effect more reliably, it ispreferable that the upper limit value of Conditional Expression (5) beset to 2.600.

On the other hand, when the correspondence value of ConditionalExpression (5) is smaller than the lower limit value, the power of thefifth lens group with respect to the fourth lens group is increased, andit may be difficult to correct curvature of field. In order to obtainthe effect reliably, it is preferable that the lower limit value ofConditional Expression (5) be set to 0.350. Moreover, in order to obtainthe effect more reliably, it is preferable that the lower limit value ofConditional Expression (5) be set to 0.450.

Moreover, it is preferable that the zoom lens satisfy ConditionalExpression (6) below.0.500<f4/f2<10.000  (6)

where

f4: a focal length of the fourth lens group

f2: a focal length of the second lens group

Conditional Expression (6) is a conditional expression for defining anappropriate range of the ratio of the focal length of the fourth lensgroup to the focal length of the second lens group. When ConditionalExpression (6) is satisfied, it is possible to realize a brightness ofan F-number of approximately F2.8 to F4.0 and a wide angle of view andto correct various aberrations including spherical aberrationsatisfactorily.

When the correspondence value of Conditional Expression (6) exceeds theupper limit value, the power of the second lens group with respect tothe fourth lens group is increased and it may be difficult to correctspherical aberration and coma aberration in the telephoto end stateparticularly. In order to obtain the effect reliably, it is preferablethat the upper limit value of Conditional Expression (6) be set to8.000. Moreover, in order to obtain the effect more reliably, it ispreferable that the upper limit value of Conditional Expression (6) beset to 6.000.

On the other hand, when the correspondence value of ConditionalExpression (6) is smaller than the lower limit value, the power of thefourth lens group with respect to the second lens group is increased andit may be difficult to correct spherical aberration and coma aberrationin the wide-angle end state particularly. In order to obtain the effectreliably, it is preferable that the lower limit value of ConditionalExpression (6) be set to 0.800. Moreover, in order to obtain the effectmore reliably, it is preferable that the lower limit value ofConditional Expression (6) be set to 1.100.

Moreover, in the zoom lens, it is preferable that the fifth lens groupincludes a meniscus-shaped positive lens having a convex surfaceoriented toward the image side and satisfy Conditional Expression (7)below.1.100<(r1+r2)/(r1−r2)<5.000  (7)

where

r1: a radius of curvature of an object-side surface of the positive lens

r2: a radius of curvature of an image-side surface of the positive lens

Conditional Expression (7) is a conditional expression for defining ashape factor of the positive lens of the fifth lens group. WhenConditional Expression (7) is satisfied, it is possible to realize abrightness of an F-number of approximately F2.8 to F4.0 and a wide angleof view and to correct various aberrations including sphericalaberration satisfactorily.

When the correspondence value of Conditional Expression (7) exceeds theupper limit value, the power of the positive lens is decreased and thevarying magnification burden of lenses other than the positive lenswithin the fifth lens group or the varying magnification burden of lensgroups other than the fifth lens group is increased. The power of thefourth lens group particularly is increased and it may be difficult tocorrect coma aberration. In order to obtain the effect reliably, it ispreferable that the upper limit value of Conditional Expression (7) beset to 4.200. Moreover, in order to obtain the effect more reliably, itis preferable that the upper limit value of Conditional Expression (7)be set to 3.400.

On the other hand, when the correspondence value of ConditionalExpression (7) is smaller than the lower limit value, the power of thepositive lens is increased, deflection of off-axis light passing throughthe positive lens is increased, and it may be difficult to correctcurvature of field. In order to obtain the effect reliably, it ispreferable that the lower limit value of Conditional Expression (7) beset to 1.400. Moreover, in order to obtain the effect more reliably, itis preferable that the lower limit value of Conditional Expression (7)be set to 1.700.

Moreover, in the zoom lens, it is preferable that at least one lens ofthe third lens group be configured to be movable so as to include acomponent in a direction orthogonal to the optical axis. For example, inthe zoom lens, it is preferable that at least two lenses of the thirdlens group be configured to be movable so as to include a component inthe direction orthogonal to the optical axis.

As described above, when at least two lenses of the third lens group areconfigured to be movable so as to include a component in the directionorthogonal to the optical axis as a vibration-reduction lens group, itis possible to decrease the size of a vibration-reduction lens group andto satisfactorily correct eccentric coma aberration (decentering comaaberration), curvature of eccentric field, and eccentric magnificationchromatic aberration (decentering lateral chromatic aberration) duringvibration reduction.

Moreover, in the zoom lens, it is preferable that at least one lens ofthe second lens group be configured to be movable so as to include acomponent in a direction orthogonal to the optical axis. For example, inthe zoom lens, it is preferable that at least one lens of the secondlens group be configured to be movable so as to include a component inthe direction orthogonal to the optical axis.

As described above, when at least two lenses of the second lens groupare configured to be movable so as to include a component in thedirection orthogonal to the optical axis as a vibration-reduction lensgroup, it is possible to decrease the size of a vibration-reduction lensgroup and to satisfactorily correct eccentric coma aberration, curvatureof eccentric field, and eccentric magnification chromatic aberrationduring vibration reduction.

Moreover, in the zoom lens, it is preferable that at least one lens ofthe fourth lens group be configured to be movable so as to include acomponent in a direction orthogonal to the optical axis. For example, inthe zoom lens, it is preferable that at least one lens of the fourthlens group be configured to be movable so as to include a component inthe direction orthogonal to the optical axis.

As described above, when at least two lenses of the fourth lens groupare configured to be movable so as to include a component in thedirection orthogonal to the optical axis as a vibration-reduction lensgroup, it is possible to decrease the size of a vibration-reduction lensgroup and to satisfactorily correct eccentric coma aberration, curvatureof eccentric field, and eccentric magnification chromatic aberrationduring vibration reduction.

Moreover, it is preferable that the zoom lens perform focusing from anobject at infinity to an object at a close distance by moving at leastone lens of the second lens group along the optical axis. For example,it is preferable that the zoom lens perform focusing from an object atinfinity to an object at a close distance by moving at least one lens ofthe second lens group along the optical axis.

Due to this configuration, it is possible to decrease the size of afocusing lens group and to satisfactorily correct variation in chromaticaberration and variation in curvature of field due to focusing.

Moreover, it is preferable that the zoom lens perform focusing from anobject at infinity to an object at a close distance by moving at leastone lens of the third lens group along the optical axis. For example, itis preferable that the zoom lens perform focusing from an object atinfinity to an object at a close distance by moving at least one lens ofthe third lens group along the optical axis.

Due to this configuration, it is possible to decrease the size of afocusing lens group and to satisfactorily correct variation in chromaticaberration and variation in curvature of field due to focusing.

Moreover, it is preferable that the zoom lens perform focusing from anobject at infinity to an object at a close distance by moving at leastone lens of the fourth lens group along the optical axis. For example,it is preferable that the zoom lens perform focusing from an object atinfinity to an object at a close distance by moving at least one lens ofthe fourth lens group along the optical axis.

Due to this configuration, it is possible to decrease the size of afocusing lens group and to satisfactorily correct variation in chromaticaberration and variation in curvature of field due to focusing.

Moreover, it is preferable that the zoom lens perform focusing from anobject at infinity to an object at a close distance by moving a portionof the fifth lens group or the entire fifth lens group along the opticalaxis.

Due to this configuration, it is possible to satisfactorily correctvariation in axial chromatic aberration, variation in sphericalaberration, and variation in coma aberration due to focusing.

Moreover, it is preferable that the zoom lens include an aperture stopdisposed between the second lens group and the third lens group.

Due to this configuration, it is possible to satisfactorily correctspherical aberration, coma aberration, and magnification chromaticaberration.

Moreover, an optical apparatus includes the zoom lens having theabove-described configuration. Due to this, it is possible to implementan optical apparatus having an F-number for brightness and an excellentoptical performance.

There is also provided a method for manufacturing a zoom lens including,in order from an object along an optical axis, a first lens group havinga negative refractive power, a second lens group having a positiverefractive power, a third lens group having a negative refractive power,a fourth lens group, and a fifth lens group, wherein when the zoom lensperforms varying magnification, the distance between the first andsecond lens groups changes, the distance between the second and thirdlens groups changes, the distance between the third and fourth lensgroups changes, the distance between the fourth and fifth lens groupschanges, the second and fourth lens groups move along the sametrajectory along the optical axis, and at least the third lens groupmoves along the optical axis. In an example, the fourth lens group has apositive refractive power and the fifth lens group has a positiverefractive power.

Alternatively, there is provided a method for manufacturing a zoom lensincluding, in order from an object along an optical axis, a first lensgroup having a negative refractive power, a second lens group having apositive refractive power, a third lens group having a negativerefractive power, a fourth lens group having a positive refractivepower, and a fifth lens group having a positive refractive power,wherein when the zoom lens performs varying magnification from awide-angle end state to a telephoto end state, the second and fourthlens groups move by the same distance along the optical axis, and atleast the third lens group moves along the optical axis.

With these zoom lens manufacturing methods, it is possible tomanufacture a zoom lens having an F-number for brightness and anexcellent optical performance.

NUMBERED EXAMPLES

Hereinafter, a zoom lens according to numbered examples will bedescribed with reference to the accompanying drawings.

Example 1

FIG. 1 is a cross-sectional view of a zoom lens according to Example 1,wherein parts (a), (b), and (d) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

Arrows under each lens group in FIG. 1(a) indicate the moving directionsof each lens group upon varying magnification from the wide-angle endstate to the intermediate focal length state. Arrows under each lensgroup in FIG. 1(b) indicate the moving directions of each lens groupupon varying magnification from the intermediate focal length state tothe telephoto end state.

As illustrated in FIG. 1(a), a zoom lens according to this example isconstituted by, in order from an object along an optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, a third lens group G3 having anegative refractive power, a fourth lens group G4 having a positiverefractive power, and a fifth lens group G5 having a positive refractivepower.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a biconcavelens L13, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a second F lens group G2F having a positiverefractive power and a second R lens group G2R having a positiverefractive power.

The second F lens group G2F is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side and a negative meniscus lens L23 having a convexsurface oriented toward the object side. The biconvex lens L21 is anaspherical lens of which the object-side lens surface is an asphericalsurface.

The second R lens group G2R is constituted by, in order from the objectalong the optical axis, a cemented lens including a negative meniscuslens L24 having a convex surface oriented toward the object side, abiconvex lens L25, and a negative meniscus lens L26 having a concavesurface oriented toward the object side.

The third lens group G3 is constituted by, in order from the objectalong the optical axis, an aperture stop S, a cemented lens including abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side, and a flare-cut diaphragm FS.The positive meniscus lens L32 is an aspherical lens of which theimage-side lens surface is an aspherical surface.

The fourth lens group G4 includes, in order from the object along theoptical axis, a cemented lens including a biconvex lens L41 and anegative meniscus lens L42 having a concave surface oriented toward theobject side and a cemented lens including a negative meniscus lens L43having a convex surface oriented toward the object side and a positivemeniscus lens L44 having a convex surface oriented toward the objectside. The negative meniscus lens L42 is an aspherical lens of which theimage-side lens surface is an aspherical surface.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, and thefourth lens group G4 move along the optical axis in relation to theimage plane I such that the distance between the first and second lensgroups G1 and G2 decreases, the distance between the second and thirdlens groups G2 and G3 increases, the distance between the third andfourth lens groups G3 and G4 decreases, and the distance between thefourth and fifth lens groups G4 and G5 increases. Specifically, when thezoom lens performs varying magnification, the first lens group G1 ismoved toward the image plane I and is then moved toward the object side,the second and fourth lens groups G2 and G4 are moved integrally towardthe object side, the third lens group G3 is moved toward the objectside, and the fifth lens group G5 is immovable in relation to the imageplane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved together with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thesecond F lens group G2F toward the image plane I.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the cemented lens of the third lens group G3 including thebiconcave lens L31 and the positive meniscus lens L32 having a convexsurface oriented toward the object side as a vibration-reduction lensgroup in such a direction as to include a component in the directionorthogonal to the optical axis.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 0.56 and the focal lengthis 16.48 (mm) (see Table 2 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.81°is 0.42 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 0.70 and the focal length is25.21 (mm) (see Table 2 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.41 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 0.87 and the focal length is 33.95 (mm) (seeTable 2 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.38 (mm).

Table 1 below illustrates the specification values of the zoom lensaccording to Example 1.

In [Overall Specification] in Table 1, f indicates the focal length ofan entire system of the zoom lens, FNO indicates the F-number, ωindicates a half-angle of view (unit: degrees), Y indicates an imageheight, TL indicates a total optical system length, and BF indicates theback focus. Here, the total optical system length TL is the distance onthe optical axis from the lens surface closest to object, of the firstlens group G1 to the image plane I. Moreover, the back focus BF is thedistance on the optical axis from the lens surface closest to image, ofthe fifth lens group G5 to the image plane I. Moreover, W indicates thefocal length state in the wide-angle end state, M indicates the focallength state in the intermediate focal length state, and T indicates thefocal length state in the telephoto end state.

In [Surface Data], a surface number indicates a sequence number of alens surface counted from the object side, r indicates the radius ofcurvature of a lens surface, d indicates the distance between lenssurfaces, nd indicates the refractive index for the d-line (wavelength:λ=587.6 nm), and νd indicates the Abbe number for the d-line(wavelength: λ=587.6 nm). Moreover, object plane indicates the objectplane, a diaphragm indicates an aperture stop S, FS indicates aflare-cut diaphragm FS, image plane indicates the image plane I. Theradius of curvature r=∞ indicates a flat surface and the refractiveindex of air (d=1.00000) is not illustrated. Moreover, when the lenssurface is an aspherical surface, a mark “*” is assigned to the surfacenumber and a paraxial radius of curvature is shown in the radius ofcurvature column r.

In [Lens Group Data], the starting surface number and the focal lengthof each lens group are shown.

In [Aspheric Data], the aspheric coefficient and the conic constant areshown when the shape of the aspherical surface shown in [Surface Data]is expressed by the following expression.x=(h ² /r)/[1+{1−κ(h/r)²}^(1/2)]+A4h ⁴ +A6h ⁶ +A8h ⁸ +A10h ¹⁰

Here, h is the height in the direction orthogonal to the optical axis, xis the distance (the amount of sag) along the optical axis directionfrom a tangential plane at the vertex of an aspherical surface at theheight h to the aspherical surface, κ indicates a conic constant, andA4, A6, A8, and A10 indicate aspheric coefficients, and r indicates aradius of curvature (a paraxial radius of curvature) of a referencespherical surface. Moreover, “E-n” indicates “×10^(−n),” and forexample, 1.234E-05=1.234×10⁻⁵. An aspheric coefficient A2 at degree 2 is0 and is not illustrated.

In [Variable Distance Data], f indicates the focal length of an entiresystem of the zoom lens, β indicates the imaging magnification, and doindicates a variable surface distance between an n-th surface and an(n+1)th surface (n is an integer). Moreover, d0 indicates the distancefrom an object to a lens surface closest to the object. Moreover, Windicates the wide-angle end state, M indicates the intermediate focallength state, and T indicates the telephoto end state. Moreover,Infinity indicates the state upon focusing on an object at infinity andClose point indicates the state upon focusing on an object at a closepoint.

In [Conditional Expression Correspondence Values], the correspondencevalues of each conditional expression are shown.

Here, “mm” is generally used as the unit of the focal length f, theradius of curvature r, and other lengths shown in Table 1. However, theunit is not limited to this since an equivalent optical performance isobtained even when the optical system is proportionally expanded orreduced.

The same symbols as in Table 1 described above are used in Tables ofother examples to be described later.

TABLE 1 Example 1 [Overall Specification] W M T f 16.48 25.21 33.95 FNO2.83 2.83 2.83 ω 54.0 40.0 31.8 Y 21.64 21.64 21.64 TL 162.361 156.840162.363 BF 18.070 18.065 18.063 [Surface Data] Surface number r d nd νdObject plane ∞  *1) 73.22991 2.000 1.85135 40.1  *2) 19.62926 7.474  3)61.15202 2.000 1.90043 37.4  4) 26.50584 12.785  5) −37.55896 2.0001.49782 82.6  6) 312.93830 0.150  7) 97.61558 6.381 2.00100 29.1  8)−90.94529 (Variable)  *9) 45.42754 8.894 1.58313 59.4  10) −33.861781.500 1.65160 58.6  11) −73.70296 1.496  12) 108.06528 1.500 1.5174252.2  13) 36.32590 (Variable)  14) 27.56863 1.500 1.84416 24.0  15)20.91099 12.393 1.48749 70.3  16) −40.66843 1.500 1.80328 25.5  17)−63.71042 (Variable)  18) (Diaphragm) ∞ 3.500  19) −208.49060 1.5001.74400 44.8  20) 26.99771 3.953 1.80244 25.6 *21) 62.64116 1.000  22)(FS) ∞ (Variable)  23) 26.91271 7.631 1.49782 82.6  24) −57.70103 1.5001.88202 37.2 *25) −93.99278 0.150  26) 62.42449 1.500 1.90043 37.4  27)19.07512 7.749 1.49782 82.6  28) 83.05930 (Variable) *29) −135.000005.076 1.77250 49.5 *30) −44.25074 (BF) Image plane ∞ [Lens Group Data]Starting surface Focal distance G1  1 −26.24 G2  9 40.29 G3 18 −70.00 G423 92.95 G5 29 83.19 [Aspheric Data]   Surface number: 1  κ =7.56000E−02  A4 = −2.78471E−06  A6 = 3.86364E−09  A8 = −2.69774E−12 A10= 9.05111E−16 Surface number: 2  κ = 1.77500E−01  A4 = −2.58137E−06  A6= 2.51888E−09  A8 = 2.34244E−12 A10 = 1.66721E−16 Surface number: 9  κ =1.00000E+00  A4 = −2.97350E−06  A6 = −1.01164E−09  A8 = 5.03482E−12 A10= −6.96957E−15 Surface number: 21  κ = 1.27800E+00  A4 = −2.19664E−07 A6 = −2.34247E−08  A8 = 1.80346E−10 A10 = −4.74051E−13 Surface number:25  κ = 1.00000E+00  A4 = 1.15418E−05  A6 = 5.82895E−09  A8 =−4.75474E−12 A10 = −1.24299E−13 Surface number: 29  κ = 1.00000E+00  A4= 1.07645E−05  A6 = −4.55699E−08  A8 = 1.31690E−10 A10 = 1.37085E−13Surface number: 30  κ = 1.00000E+00  A4 = 1.60203E−05  A6 = −5.49184E−08 A8 = 1.40358E−10 A10 = −1.35750E−13 [Variable Distance Data] W M T W MT Infinity Infinity Infinity Close point Close point Close point d0 ∞ ∞∞ 110.01 115.53 110.00 β — — — −0.1220 −0.1816 −0.2566 f 16.48 25.2133.95 — — — d8 28.899 9.423 0.500 33.772 14.498 6.164 d13 6.862 6.8626.862 1.989 1.787 1.198 d17 2.000 5.572 7.582 2.000 5.572 7.582 d227.082 3.510 1.500 7.082 3.510 1.500 d28 4.315 18.275 32.723 4.315 18.27532.723 BF 18.070 18.065 18.063 18.155 18.254 18.438 [ConditionalExpression Correspondence Values] (1) (−f3)/fw = 4.248 (2) |m34|/fw =0.339 (3) f5/(−f1) = 3.171 (4) |m12|/fw = 1.723 (5) f5/f4 = 0.895 (6)f4/f2 = 2.307 (7) (r1 + r2)/(r1 − r2) = 1.975

FIG. 2 shows graphs illustrating various aberrations of the zoom lensaccording to Example 1 upon focusing on an object at infinity, whereinparts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 3 shows graphs illustrating various aberrations of the zoom lensaccording to Example 1 upon focusing on an object at a close point,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 4 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 1 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

In the graphs illustrating respective aberrations, FNO indicates theF-number, A indicates an incidence angle of light (that is, a half-angleof view (unit: °), NA indicates a numerical aperture, and H0 indicatesan object height (unit: mm). In the drawings, d indicates the aberrationcurves at the d-line (wavelength: λ=587.6 nm), g indicates theaberration curves at the g-line (wavelength: λ=435.8 nm), andaberrations without these characters indicate aberration curves at thed-line. The spherical aberration graphs illustrate the F-number valuescorresponding to the maximum aperture. The astigmatism diagrams and thedistortion diagrams illustrate the maximum values at the half-angle ofview or the object height. The lateral aberration diagrams illustratethe values of each half-angle of view or each object height. In theastigmatism diagrams, a solid line indicates the sagittal image planeand a broken line indicates the meridional image plane. Moreover, thelateral aberration diagrams illustrate the meridional lateral aberrationat the d-line and the g-line. The same reference symbols as in thisexample are used in the aberration graphs of respective examples to bedescribed later.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 1 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

Example 2

FIG. 5 is a cross-sectional view of a zoom lens according to Example 2,wherein parts (a), (b), and (d) are, wherein parts (a), (b), and (d) arein a wide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

Arrows under each lens group in FIG. 5(a) indicate the moving directionsof each lens group upon varying magnification from the wide-angle endstate to the intermediate focal length state. Arrows under each lensgroup in FIG. 5(b) indicate the moving directions of each lens groupupon varying magnification from the intermediate focal length state tothe telephoto end state.

As illustrated in FIG. 5(a), a zoom lens according to this example isconstituted by, in order from the object along the optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, a third lens group G3 having anegative refractive power, a fourth lens group G4 having a positiverefractive power, and a fifth lens group G5 having a positive refractivepower.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a biconcavelens L13, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a second F lens group G2F having a positiverefractive power and a second R lens group G2R having a positiverefractive power.

The second F lens group G2F is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side and a negative meniscus lens L23 having a convexsurface oriented toward the object side. The biconvex lens L21 is anaspherical lens of which the object-side lens surface is an asphericalsurface.

The second R lens group G2R is constituted by, in order from the objectalong the optical axis, a cemented lens including a negative meniscuslens L24 having a convex surface oriented toward the object side, abiconvex lens L25, and a negative meniscus lens L26 having a concavesurface oriented toward the object side.

The third lens group G3 is constituted by, in order from the objectalong the optical axis, an aperture stop S, a cemented lens including abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side, and a flare-cut diaphragm FS.The positive meniscus lens L32 is an aspherical lens of which theimage-side lens surface is an aspherical surface.

The fourth lens group G4 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L41and a negative meniscus lens L42 having a concave surface orientedtoward the object side and a cemented lens including a negative meniscuslens L43 having a convex surface oriented toward the object side and apositive meniscus lens L44 having a convex surface oriented toward theobject side. The negative meniscus lens L42 is an aspherical lens ofwhich the image-side lens surface is an aspherical surface.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, the fourthlens group G4, and the fifth lens group G5 move along the optical axisin relation to the image plane I such that the distance between thefirst and second lens groups G1 and G2 decreases, the distance betweenthe second and third lens groups G2 and G3 increases, the distancebetween the third and fourth lens groups G3 and G4 decreases, and thedistance between the fourth and fifth lens groups G4 and G5 increases.Specifically, when the zoom lens performs varying magnification, thefirst lens group G1 is moved toward the image plane I and is then movedtoward the object side, the second and fourth lens groups G2 and G4 aremoved integrally toward the object side, the third lens group G3 ismoved toward the object side, and the fifth lens group G5 is movedtoward the object side and is then moved toward the image plane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved together with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thesecond F lens group G2F toward the image plane I.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the cemented lens of the third lens group G3 including thebiconcave lens L31 and the positive meniscus lens L32 having a convexsurface oriented toward the object side as a vibration-reduction lensgroup in such a direction as to include a component in the directionorthogonal to the optical axis.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 0.56 and the focal lengthis 16.48 (mm) (see Table 3 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.81°is 0.42 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 0.70 and the focal length is25.21 (mm) (see Table 3 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.41 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 0.87 and the focal length is 33.95 (mm) (seeTable 3 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.39 (mm).

Table 2 below illustrates the specification values of the zoom lensaccording to Example 2.

TABLE 2 Example 2 [Overall Specification] W M T f 16.48 25.21 33.95 FNO2.83 2.83 2.83 ω 54.0 39.9 31.7 Y 21.64 21.64 21.64 TL 162.369 156.568162.359 BF 18.069 18.479 18.059 [Surface Data] Surface number r d nd νdObject plane ∞  *1) 73.35843 2.000 1.85135 40.1  *2) 19.65231 7.423  3)60.85659 2.000 1.90043 37.4  4) 26.46067 12.865  5) −37.68469 2.0001.49782 82.6  6) 319.60622 0.150  7) 98.35638 6.315 2.00100 29.1  8)−91.84642 (Variable)  *9) 45.12179 9.169 1.58313 59.4  10) −32.359181.500 1.65160 58.6  11) −70.79534 1.426  12) 116.36340 1.500 1.5174252.2  13) 36.40999 (Variable)  14) 27.76490 1.500 1.84500 23.9  15)21.11208 12.352 1.48749 70.3  16) −40.48676 1.500 1.79173 26.0  17)−63.27082 (Variable)  18) (Diaphragm) ∞ 3.500  19) −209.12746 1.5001.74400 44.8  20) 27.47317 3.887 1.80244 25.6 *21) 62.77212 1.000  22)(FS) ∞ (Variable)  23) 26.82011 7.501 1.49782 82.6  24) −55.69746 1.5001.88202 37.2 *25) −89.72149 0.150  26) 63.20031 1.500 1.90043 37.4  27)19.07631 7.703 1.49782 82.6  28) 80.36061 (Variable) *29) −135.000005.077 1.77250 49.5 *30) −44.25947 (BF) Image plane ∞ [Lens Group Data]Starting surface Focal distance G1  1 −26.11 G2  9 40.20 G3 18 −70.00 G423 93.63 G5 29 83.21 [Aspheric Data]   Surface number: 1  κ =8.75000E−02  A4 = −2.78056E−06  A6 = 3.66529E−09  A8 = −2.32659E−12 A10= 7.29739E−16 Surface number: 2  κ = 1.25600E−01  A4 = −1.66529E−06  A6= 1.18889E−09  A8 = 5.12891E−12 A10 = −1.72885E−16 Surface number: 9  κ= 1.00000E+00  A4 = −3.12858E−06  A6 = −1.15459E−09  A8 = 5.52871E−12A10 = −7.23502E−15 Surface number: 21  κ = 1.36390E+00  A4 =−1.54769E−07  A6 = −2.66171E−08  A8 = 2.07963E−10 A10 = −5.54299E−13Surface number: 25  κ = 1.00000E+00  A4 = 1.15286E−05  A6 = 7.02471E−09 A8 = −1.60325E−11 A10 = −9.68792E−14 Surface number: 29  κ =1.00000E+00  A4 = 1.12240E−05  A6 = −4.41692E−08  A8 = 1.19461E−10 A10 =−1.22999E−13 Surface number: 30  κ = 1.00000E+00  A4 = 1.62814E−05  A6 =−5.22346E−08  A8 = 1.25318E−10 A10 = −1.19716E−13 [Variable DistanceData] W M T W M T Infinity Infinity Infinity Close point Close pointClose point d0 ∞ ∞ ∞ 110.00 115.79 110.00 β — — — −0.1221 −0.1814−0.2567 f 16.48 25.21 33.95 — — — d8 28.797 9.141 0.500 33.624 14.1696.113 d13 6.847 6.847 6.847 2.020 1.820 1.234 d17 2.000 5.812 7.7922.000 5.812 7.792 d22 7.292 3.480 1.500 7.292 3.480 1.500 d28 4.34617.791 32.643 4.346 17.791 32.643 BF 18.069 18.479 18.059 18.154 18.66718.434 [Conditional Expression Correspondence Values] (1) (−f3)/fw =4.248 (2) |m34|/fw = 0.351 (3) f5/(−f1) = 3.187 (4) |m12|/fw = 1.717 (5)f5/f4 = 0.889 (6) f4/f2 = 2.329 (7) (r1 + r2)/(r1 − r2) = 1.976

FIG. 6 shows graphs illustrating various aberrations of the zoom lensaccording to Example 2 upon focusing on an object at infinity, whereinparts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 7 shows graphs illustrating various aberrations of the zoom lensaccording to Example 2 upon focusing on an object at a close point,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 8 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 2 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 2 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

Example 3

FIG. 9 is a cross-sectional view of a zoom lens according to Example 3,wherein parts (a), (b), and (d) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

Arrows under each lens group in FIG. 9(a) indicate the moving directionsof each lens group upon varying magnification from the wide-angle endstate to the intermediate focal length state. Arrows under each lensgroup in FIG. 9(b) indicate the moving directions of each lens groupupon varying magnification from the intermediate focal length state tothe telephoto end state.

As illustrated in FIG. 9(a), a zoom lens according to this example isconstituted by, in order from an object along an optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, a third lens group G3 having anegative refractive power, a fourth lens group G4 having a positiverefractive power, and a fifth lens group G5 having a positive refractivepower.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a biconcavelens L13, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a second F lens group G2F having a positiverefractive power and a second R lens group G2R having a positiverefractive power.

The second F lens group G2F is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side and a negative meniscus lens L23 having a convexsurface oriented toward the object side. The biconvex lens L21 is anaspherical lens of which the object-side lens surface is an asphericalsurface.

The second R lens group G2R is constituted by, in order from the objectalong the optical axis, a cemented lens including a negative meniscuslens L24 having a convex surface oriented toward the object side, abiconvex lens L25, and a negative meniscus lens L26 having a concavesurface oriented toward the object side.

The third lens group G3 is constituted by, in order from the objectalong the optical axis, an aperture stop S, a cemented lens including abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side, and a flare-cut diaphragm FS.The positive meniscus lens L32 is an aspherical lens of which theimage-side lens surface is an aspherical surface.

The fourth lens group G4 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L41and a negative meniscus lens L42 having a concave surface orientedtoward the object side and a cemented lens including a negative meniscuslens L43 having a convex surface oriented toward the object side and apositive meniscus lens L44 having a convex surface oriented toward theobject side. The negative meniscus lens L42 is an aspherical lens ofwhich the image-side lens surface is an aspherical surface.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, and thefourth lens group G4 move along the optical axis in relation to theimage plane I such that the distance between the first and second lensgroups G1 and G2 decreases, the distance between the second and thirdlens groups G2 and G3 increases, the distance between the third andfourth lens groups G3 and G4 decreases, and the distance between thefourth and fifth lens groups G4 and G5 increases. Specifically, when thezoom lens performs varying magnification, the first lens group G1 ismoved toward the image plane I and is then moved toward the object side,the second and fourth lens groups G2 and G4 are moved integrally towardthe object side, the third lens group G3 is moved toward the objectside, and the fifth lens group G5 is immovable in relation to the imageplane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved together with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thesecond F lens group G2F toward the image plane I.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the cemented lens of the third lens group G3 including thebiconcave lens L31 and the positive meniscus lens L32 having a convexsurface oriented toward the object side in such a direction as toinclude a component in the direction orthogonal to the optical axis as avibration-reduction lens group.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 0.81 and the focal lengthis 18.54 (mm) (see Table 4 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.77°is 0.30 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 1.00 and the focal length is25.21 (mm) (see Table 4 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.29 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 1.26 and the focal length is 33.95 (mm) (seeTable 4 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.27 (mm).

Table 3 below illustrates the specification values of the zoom lensaccording to Example 3.

TABLE 3 Example 3 [Overall Specification] W M T f 18.54 25.21 33.95 FNO2.83 2.83 2.83 ω 49.9 40.1 31.7 Y 21.64 21.64 21.64 TL 160.545 157.622162.364 BF 18.069 18.074 18.064 [Surface Data] Surface number r d nd νdObject plane ∞  *1) 64.13853 2.000 1.82080 42.7  *2) 20.52237 7.450  3)42.79628 2.000 1.84300 37.4  4) 23.01367 14.005  5) −42.12649 2.0001.49782 82.6  6) 60.80104 0.150  7) 55.48158 6.486 2.00100 29.1  8)−197.93506 (Variable)  *9) 46.12318 12.702 1.58313 59.4  10) −26.660641.500 1.61772 49.8  11) −71.59323 0.150  12) 68.72530 1.500 1.51742 52.2 13) 35.19343 (Variable)  14) 27.39712 1.500 1.84666 23.8  15) 20.2627411.974 1.48749 70.3  16) −34.96195 1.500 1.80000 25.6  17) −55.58525(Variable)  18) (Diaphragm) ∞ 4.000  19) −144.55027 1.500 1.74400 44.8 20) 20.23731 4.012 1.80244 25.6 *21) 40.54944 1.000  22) (FS) ∞(Variable)  23) 29.62933 6.997 1.49782 82.6  24) −75.50908 1.500 1.8820237.2 *25) −112.41227 0.150  26) 34.10106 1.500 1.90043 37.4  27)19.08383 7.811 1.49782 82.6  28) 56.03390 (Variable) *29) −135.000004.569 1.77250 49.5 *30) −51.50452 (BF) Image plane ∞ [Lens Group Data]Starting surface Focal distance G1  1 −26.00 G2  9 38.17 G3 18 −45.00 G423 54.97 G5 29 105.29 [Aspheric Data]   Surface number: 1  κ =1.97190E+00  A4 = −3.80899E−06  A6 = 3.65826E−09  A8 = −2.38771E−12 A10= 7.43869E−16 Surface number: 2  κ = 8.82000E−02  A4 = −1.21936E−06  A6= 2.60285E−09  A8 = 9.42881E−13 A10 = 3.22230E−15 Surface number: 9  κ =1.00000E+00  A4 = −3.25645E−06  A6 = 5.35394E−10  A8 = 0.00000E+00 A10 =0.00000E+00 Surface number: 21  κ = 4.59700E−01  A4 = −1.02727E−06  A6 =−1.01707E−08  A8 = 9.24484E−11 A10 = −2.40570E−13 Surface number: 25  κ= 1.00000E+00  A4 = 9.28617E−06  A6 = 1.98222E−09  A8 = 3.47233E−11 A10= −1.62414E−13 Surface number: 29  κ = 1.00000E+00  A4 = 8.29178E−06  A6= −3.50865E−08  A8 = 1.26307E−10 A10 = −1.60070E−13 Surface number: 30 κ = 1.00000E+00  A4 = 1.30379E−05  A6 = −4.40208E−08  A8 = 1.33306E−10A10 = −1.56261E−13 [Variable Distance Data] W M T W M T InfinityInfinity Infinity Close point Close point Close point d0 ∞ ∞ ∞ 111.82114.75 110.00 β — — — −0.1327 −0.1788 −0.2514 f 18.54 25.21 33.95 — — —d8 22.618 9.438 0.500 27.248 14.104 5.591 d13 8.395 8.395 8.395 3.7663.729 3.304 d17 3.500 5.288 6.734 3.500 5.288 6.734 d22 4.734 2.9461.500 4.734 2.946 1.500 d28 5.273 15.525 29.215 5.273 15.525 29.215 BF18.069 18.074 18.064 18.169 18.256 18.424 [Conditional ExpressionCorrespondence Values] (1) (−f3)/fw = 2.427 (2) |m34|/fw = 0.174 (3)f5/(−f1) = 4.050 (4) |m12|/fw = 1.193 (5) f5/f4 = 1.915 (6) f4/f2 =1.442 (7) (r1 + r2)/(r1 − r2) = 2.234

FIG. 10 shows graphs illustrating various aberrations of the zoom lensaccording to Example 3 upon focusing on an object at infinity, whereinparts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 11 shows graphs illustrating various aberrations of the zoom lensaccording to Example 3 upon focusing on an object at a close point,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 12 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 3 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 3 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

Example 4

FIG. 13 is a cross-sectional view of a zoom lens according to Example 4,wherein parts (a), (b), and (d) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

Arrows under each lens group in FIG. 13(a) indicate the movingdirections of each lens group upon varying magnification from thewide-angle end state to the intermediate focal length state. Arrowsunder each lens group in FIG. 13(b) indicate the moving directions ofeach lens group upon varying magnification from the intermediate focallength state to the telephoto end state.

As illustrated in FIG. 13(a), a zoom lens according to this example isconstituted by, in order from the object along the optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, a third lens group G3 having anegative refractive power, a fourth lens group G4 having a positiverefractive power, and a fifth lens group G5 having a positive refractivepower.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a biconcavelens L13, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a second F lens group G2F having a positiverefractive power and a second R lens group G2R having a positiverefractive power.

The second F lens group G2F is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side and a negative meniscus lens L23 having a convexsurface oriented toward the object side. The biconvex lens L21 is anaspherical lens of which the object-side lens surface is an asphericalsurface.

The second R lens group G2R is constituted by, in order from the objectalong the optical axis, a cemented lens including a negative meniscuslens L24 having a convex surface oriented toward the object side, abiconvex lens L25, and a negative meniscus lens L26 having a concavesurface oriented toward the object side.

The third lens group G3 is constituted by, in order from the objectalong the optical axis, an aperture stop S, a cemented lens including abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side, and a flare-cut diaphragm FS.The positive meniscus lens L32 is an aspherical lens of which theimage-side lens surface is an aspherical surface.

The fourth lens group G4 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L41and a negative meniscus lens L42 having a concave surface orientedtoward the object side and a cemented lens including a negative meniscuslens L43 having a convex surface oriented toward the object side and apositive meniscus lens L44 having a convex surface oriented toward theobject side. The negative meniscus lens L42 is an aspherical lens ofwhich the image-side lens surface is an aspherical surface.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, and thefourth lens group G4 move along the optical axis in relation to theimage plane I such that the distance between the first and second lensgroups G1 and G2 decreases, the distance between the second and thirdlens groups G2 and G3 increases, the distance between the third andfourth lens groups G3 and G4 decreases, and the distance between thefourth and fifth lens groups G4 and G5 increases. Specifically, when thezoom lens performs varying magnification, the first lens group G1 ismoved toward the image plane I and is then moved toward the object side,the second and fourth lens groups G2 and G4 are moved integrally towardthe object side, the third lens group G3 is moved toward the objectside, and the fifth lens group G5 is immovable in relation to the imageplane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved together with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thesecond F lens group G2F toward the image plane I.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the cemented lens of the third lens group G3 including thebiconcave lens L31 and the positive meniscus lens L32 having a convexsurface oriented toward the object side in such a direction as toinclude a component in the direction orthogonal to the optical axis as avibration-reduction lens group.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 0.47 and the focal lengthis 15.45 (mm) (see Table 5 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.84°is 0.48 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 0.61 and the focal length is25.21 (mm) (see Table 5 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.48 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 0.76 and the focal length is 33.95 (mm) (seeTable 5 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.44 (mm).

Table 4 below illustrates the specification values of the zoom lensaccording to Example 4.

TABLE 4 Example 4 [Overall Specification] W M T f 15.45 25.21 33.95 FNO2.83 2.83 2.83 ω 56.2 40.0 31.8 Y 21.64 21.64 21.64 TL 168.787 161.395167.660 BF 18.067 18.070 18.058 [Surface Data] Surface number r d nd νdObject plane ∞  *1) 84.32721 2.000 1.82080 42.7  *2) 22.42250 6.533  3)40.43903 2.000 1.90043 37.4  4) 23.79897 18.443  5) −36.72174 2.0001.49782 82.6  6) 108.66132 0.150  7) 86.07473 6.091 2.00100 29.1  8)−113.52466 (Variable)  *9) 56.20536 8.334 1.58313 59.4  10) −34.827241.500 1.62896 51.8  11) −62.67282 0.150  12) 1521.91690 1.500 1.5174252.2  13) 63.48881 (Variable)  14) 32.18721 1.500 1.83207 24.9  15)23.97842 11.952 1.48749 70.3  16) −42.36534 1.500 1.79889 25.4  17)−64.06791 (Variable)  18) (Diaphragm) ∞ 4.000  19) −402.90754 1.5001.74400 44.8  20) 29.51707 4.016 1.80244 25.6 *21) 67.51202 1.000  22)(FS) ∞ (Variable)  23) 30.01453 8.025 1.49782 82.6  24) −48.32228 1.5001.88202 37.2 *25) −80.74589 0.150  26) 73.99805 1.500 1.90043 37.4  27)19.28578 8.991 1.49782 82.6  28) 131.61654 (Variable) *29) −135.000005.020 1.77250 49.5 *30) −45.90440 (BF) Image plane ∞ [Lens Group Data]Starting surface Focal distance G1  1 −26.00 G2  9 40.61 G3 18 −85.00 G423 113.40 G5 29 87.88 [Aspheric Data]   Surface number: 1  κ =1.07450E+00  A4 = −1.57852E−06  A6 = 2.55869E−09  A8 = −1.24755E−12 A10= 2.99043E−16 Surface number: 2  κ = 2.82500E−01  A4 = −5.25879E−06  A6= 2.99379E−09  A8 = −1.07006E−13 A10 = 2.38338E−15 Surface number: 9  κ= 1.00000E+00  A4 = −3.44380E−06  A6 = 6.36234E−10  A8 = 0.00000E+00 A10= 0.00000E+00 Surface number: 21  κ = 5.97700E−01  A4 = −1.14555E−08  A6= −6.90561E−09  A8 = 2.24606E−11 A10 = −2.11799E−15 Surface number: 25 κ = 1.00000E+00  A4 = 8.46457E−06  A6 = −1.83245E−09  A8 = 1.13124E−11A10 = −6.67256E−14 Surface number: 29  κ = 1.00000E+00  A4 = 1.35371E−05 A6 = −4.85133E−08  A8 = 1.04081E−10 A10 = −9.31604E−14 Surface number:30  κ = 1.00000E+00  A4 = 2.00382E−05  A6 = −5.78531E−08  A8 =1.07159E−10 A10 = −8.91147E−14 [Variable Distance Data] W M T W M TInfinity Infinity Infinity Close point Close point Close point d0 ∞ ∞ ∞103.58 110.97 104.70 β — — — −0.1177 −0.1847 −0.2625 f 15.45 25.21 33.95— — — d8 32.660 9.394 0.500 37.602 14.284 5.903 d13 6.126 6.126 6.1261.184 1.237 0.724 d17 1.500 5.658 7.190 1.500 5.658 7.190 d22 7.1903.032 1.500 7.190 3.032 1.500 d28 3.889 19.760 34.930 3.889 19.76034.930 BF 18.067 18.070 18.058 18.146 18.265 18.451 [ConditionalExpression Correspondence Values] (1) (−f3)/fw = 5.502 (2) |m34|/fw =0.368 (3) f5/(−f1) = 3.380 (4) |m12|/fw = 2.082 (5) f5/f4 = 0.775 (6)f4/f2 = 2.792 (7) (r1 + r2)/(r1 − r2) = 2.030

FIG. 14 shows graphs illustrating various aberrations of the zoom lensaccording to Example 4 upon focusing on an object at infinity, whereinparts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 15 shows graphs illustrating various aberrations of the zoom lensaccording to Example 4 upon focusing on an object at a close point,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 16 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 4 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 4 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

Example 5

FIG. 17 is a cross-sectional view of a zoom lens according to Example 5,wherein parts (a), (b), and (d) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

Arrows under each lens group in FIG. 17(a) indicate the movingdirections of each lens group upon varying magnification from thewide-angle end state to the intermediate focal length state. Arrowsunder each lens group in FIG. 17(b) indicate the moving directions ofeach lens group upon varying magnification from the intermediate focallength state to the telephoto end state.

As illustrated in FIG. 17(a), a zoom lens according to this example isconstituted by, in order from an object along an optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, a third lens group G3 having anegative refractive power, a fourth lens group G4 having a positiverefractive power, and a fifth lens group G5 having a positive refractivepower.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a biconcavelens L13, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces. The negative meniscus lens L12 isan aspherical lens of which the image-side lens surface is an asphericalsurface.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a second F lens group G2F having a positiverefractive power and a second R lens group G2R having a positiverefractive power.

The second F lens group G2F is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side and a biconcave lens L23. The biconvex lens L21is an aspherical lens of which the object-side lens surface is anaspherical surface.

The second R lens group G2R is constituted by, in order from the objectalong the optical axis, a cemented lens including a negative meniscuslens L24 having a convex surface oriented toward the object side, abiconvex lens L25, and a negative meniscus lens L26 having a concavesurface oriented toward the object side. The negative meniscus lens L24is an aspherical lens of which the object-side lens surface is anaspherical surface.

The third lens group G3 is constituted by, in order from the objectalong the optical axis, an aperture stop S, a cemented lens including abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side, and a flare-cut diaphragm FS.

The fourth lens group G4 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L41and a negative meniscus lens L42 having a concave surface orientedtoward the object side and a cemented lens including a negative meniscuslens L43 having a convex surface oriented toward the object side and apositive meniscus lens L44 having a convex surface oriented toward theobject side. The negative meniscus lens L42 is an aspherical lens ofwhich the image-side lens surface is an aspherical surface.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, and thefourth lens group G4 move along the optical axis in relation to theimage plane I such that the distance between the first and second lensgroups G1 and G2 decreases, the distance between the second and thirdlens groups G2 and G3 increases, the distance between the third andfourth lens groups G3 and G4 decreases, and the distance between thefourth and fifth lens groups G4 and G5 increases. Specifically, when thezoom lens performs varying magnification, the first lens group G1 ismoved toward the image plane I and is then moved toward the object side,the second and fourth lens groups G2 and G4 are moved integrally towardthe object side, the third lens group G3 is moved toward the objectside, and the fifth lens group G5 is immovable in relation to the imageplane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved together with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thesecond F lens group G2F toward the image plane I.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the second R lens group G2R in such a direction as to include acomponent in the direction orthogonal to the optical axis as avibration-reduction lens group.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 1.07 and the focal lengthis 16.48 (mm) (see Table 6 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.81°is 0.22 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 1.37 and the focal length is25.21 (mm) (see Table 6 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.21 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 1.67 and the focal length is 33.95 (mm) (seeTable 6 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.20 (mm).

Table 5 below illustrates the specification values of the zoom lensaccording to Example 5.

TABLE 5 Example 5 [Overall Specification] W M T f 16.48 25.21 33.95 FNO4.00 4.00 4.00 ω 54.1 39.8 31.7 Y 21.64 21.64 21.64 TL 162.369 156.678160.978 BF 18.069 18.064 18.074 [Surface Data] Surface number r d nd νdObject plane ∞  *1) 180.13769 2.000 1.82080 42.7  *2) 19.96088 6.970  3)94.52854 2.000 1.90043 37.4  *4) 28.44278 9.857  5) −42.62350 2.0001.49782 82.6  6) 244.08326 0.150  7) 61.25466 5.605 2.00100 29.1  8)−150.06559 (Variable)  *9) 36.24721 7.764 1.58313 59.4  10) −22.606891.500 1.65844 50.8  11) −43.72965 0.151  12) −207.94715 1.500 1.5174252.2  13) 40.03120 (Variable) *14) 43.25649 1.500 1.79504 28.7  15)26.23995 11.085 1.48749 70.3  16) −21.42752 1.500 1.68893 31.2  17)−29.56586 (Variable)  18) (Diaphragm) ∞ 4.000  19) −74.75529 1.5001.74400 44.8  20) 22.57348 3.362 1.80244 25.6  21) 84.92681 1.000  22)(FS) ∞ (Variable)  23) 34.18409 11.631 1.49782 82.6  24) −22.09869 1.5001.88202 37.2 *25) −35.01463 0.150  26) 64.77675 1.500 1.90043 37.4  27)18.18435 8.523 1.49782 82.6  28) 70.17847 (Variable) *29) −135.000005.121 1.77250 49.5 *30) −46.54146 (BF) Image plane ∞ [Lens Group Data]Starting surface Focal distance G1  1 −23.15 G2  9 37.14 G3 18 −58.82 G423 86.56 G5 29 89.68 [Aspheric Data]   Surface number: 1  κ =2.00000E+00  A4 = 7.91245E−06  A6 = −3.69643E−09  A8 = 1.11415E−12 A10 =−2.04281E−16 Surface number: 2  κ = 1.05500E−01  A4 = −1.07575E−05  A6 =4.04887E−08  A8 = −2.80099E−11 A10 = 8.02396E−14 Surface number: 4  κ =1.00000E+00  A4 = 2.14895E−05  A6 = 5.07570E−09  A8 = −8.70469E−11 A10 =9.89182E−14 Surface number: 9  κ = 1.00000E+00  A4 = −5.58940E−06  A6 =−6.24739E−09  A8 = 0.00000E+00 A10 = 0.00000E+00 Surface number: 14  κ =1.00000E+00  A4 = −4.10738E−06  A6 = 2.26991E−09  A8 = −1.27958E−11 A10= 2.28497E−14 Surface number: 25  κ = 1.00000E+00  A4 = 6.63910E−06  A6= −2.70332E−09  A8 = −1.14938E−11 A10 = −3.86980E−14 Surface number: 29 κ = 1.00000E+00  A4 = 2.96724E−06  A6 = −7.37447E−10  A8 = 4.28602E−11A10 = −7.07831E−14 Surface number: 30  κ = 1.00000E+00  A4 = 5.46618E−06 A6 = −9.05640E−09  A8 = 6.16567E−11 A10 = −8.57111E−14 [VariableDistance Data] W M T W M T Infinity Infinity Infinity Close point Closepoint Close point d0 ∞ ∞ ∞ 110.00 115.69 111.40 β — — — −0.1243 −0.1848−0.2589 f 16.48 25.21 33.95 — — — d8 27.344 8.875 0.500 31.204 12.8264.873 d13 7.541 7.541 7.541 3.681 3.590 3.168 d17 2.000 7.319 11.3422.000 7.319 11.342 d22 10.842 5.524 1.500 10.842 5.524 1.500 d28 4.70417.488 30.153 4.704 17.488 30.158 BF 18.069 18.064 18.074 18.157 18.25918.456 [Conditional Expression Correspondence Values] (1) (−f3)/fw =3.569 (2) |m34|/fw = 0.567 (3) f5/(−f1) = 3.873 (4) |m12|/fw = 1.629 (5)f5/f4 = 1.036 (6) f4/f2 = 2.330 (7) (r1 + r2)/(r1 − r2) = 2.052

FIG. 18 shows graphs illustrating various aberrations of the zoom lensaccording to Example 5 upon focusing on an object at infinity, whereinparts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 19 shows graphs illustrating various aberrations of the zoom lensaccording to Example 5 upon focusing on an object at a close point,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 20 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 5 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 5 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

Example 6

FIG. 21 is a cross-sectional view of a zoom lens according to Example 6in a wide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

Arrows under each lens group in FIG. 21(a) indicate the movingdirections of each lens group upon varying magnification from thewide-angle end state to the intermediate focal length state. Arrowsunder each lens group in FIG. 21(b) indicate the moving directions ofeach lens group upon varying magnification from the intermediate focallength state to the telephoto end state.

As illustrated in FIG. 21(a), a zoom lens according to this example isconstituted by, in order from an object along an optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, a third lens group G3 having anegative refractive power, a fourth lens group G4 having a positiverefractive power, and a fifth lens group G5 having a positive refractivepower.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a negativemeniscus lens L13 having a concave surface oriented toward the objectside, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a second F lens group G2F having a positiverefractive power and a second R lens group G2R having a positiverefractive power.

The second F lens group G2F is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side and a negative meniscus lens L23 having a convexsurface oriented toward the object side. The biconvex lens L21 is anaspherical lens of which the object-side lens surface is an asphericalsurface.

The second R lens group G2R is constituted by, in order from the objectalong the optical axis, a cemented lens including a negative meniscuslens L24 having a convex surface oriented toward the object side, abiconvex lens L25, and a negative meniscus lens L26 having a concavesurface oriented toward the object side.

The third lens group G3 is constituted by, in order from the objectalong the optical axis, an aperture stop S, a cemented lens including abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side, and a flare-cut diaphragm FS.The positive meniscus lens L32 is an aspherical lens of which theimage-side lens surface is an aspherical surface.

The fourth lens group G4 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L41and a negative meniscus lens L42 having a concave surface orientedtoward the object side and a cemented lens including a negative meniscuslens L43 having a convex surface oriented toward the object side and apositive meniscus lens L44 having a convex surface oriented toward theobject side. The negative meniscus lens L42 is an aspherical lens ofwhich the image-side lens surface is an aspherical surface.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, and thefourth lens group G4 move along the optical axis in relation to theimage plane I such that the distance between the first and second lensgroups G1 and G2 decreases, the distance between the second and thirdlens groups G2 and G3 increases, the distance between the third andfourth lens groups G3 and G4 decreases, and the distance between thefourth and fifth lens groups G4 and G5 increases. Specifically, when thezoom lens performs varying magnification, the first lens group G1 ismoved toward the image plane I and is then moved toward the object side,the second and fourth lens groups G2 and G4 are moved integrally towardthe object side, the third lens group G3 is moved toward the objectside, and the fifth lens group G5 is immovable in relation to the imageplane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved together with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thesecond F lens group G2F toward the image plane I.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the cemented lens of the third lens group G3 including thebiconcave lens L31 and the positive meniscus lens L32 having a convexsurface oriented toward the object side in such a direction as toinclude a component in the direction orthogonal to the optical axis as avibration-reduction lens group.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 0.56 and the focal lengthis 16.48 (mm) (see Table 7 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.81°is 0.42 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 0.70 and the focal length is25.21 (mm) (see Table 7 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.41 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 0.87 and the focal length is 33.95 (mm) (seeTable 7 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.39 (mm).

Table 6 below illustrates the specification values of the zoom lensaccording to Example 6.

TABLE 6 Example 6 [Overall Specification] W M T f 16.48 25.21 33.95 FNO4.00 4.00 4.00 ω 54.0 39.8 31.8 Y 21.64 21.64 21.64 TL 152.197 148.076154.253 BF 18.060 18.054 18.063 [Surface Data] Surface number r d nd νdObject plane ∞  *1) 89.63662 2.000 1.82080 42.7  *2) 19.03463 6.400  3)59.00594 2.000 1.90043 37.4  4) 25.04291 12.879  5) −34.42001 2.0001.49782 82.6  6) −220.10809 0.150  7) 110.12188 5.234 2.00100 29.1  8)−94.03704 (Variable)  *9) 34.70954 8.195 1.58313 59.4  10) −22.327021.500 1.64013 58.3  11) −56.97811 0.150  12) 143.57014 1.500 1.5174252.2  13) 29.47978 (Variable)  14) 25.69484 1.500 1.79504 28.7  15)18.31640 7.768 1.48749 70.3  16) −37.27717 1.500 1.73708 28.4  17)−69.75583 (Variable)  18) (Diaphragm) ∞ 4.000  19) −172.99604 1.5001.74400 44.8  20) 25.25276 3.145 1.80244 25.6 *21) 65.66381 1.000  22)(FS) ∞ (Variable)  23) 28.13736 7.994 1.49782 82.6  24) −39.84408 1.5001.88202 37.2 *25) −55.75469 0.150  26) 79.86144 1.500 1.90043 37.4  27)18.03173 8.303 1.49782 82.6  28) 109.39627 (Variable) *29) −135.000005.201 1.77250 49.5 *30) −43.87168 (BF) Image plane ∞ [Lens Group Data]Starting surface Focal distance G1  1 −25.31 G2  9 38.11 G3 18 −70.00 G423 97.42 G5 29 82.09 [Aspheric Data]   Surface number: 1  κ =0.00000E+00  A4 = −1.65798E−06  A6 = 2.891887E−09  A8 = −2.10545E−12 A10= 1.01969E−15 Surface number: 2  κ = 1.52100E−01  A4 = −3.98735E−06  A6= 1.20818E−08  A8 = −2.50960E−11 A10 = 4.32957E−14 Surface number: 9  κ= 1.00000E+00  A4 = −5.15908E−06  A6 = 1.64281E−09  A8 = 0.00000E+00 A10= 0.00000E+00 Surface number: 21  κ = 1.89270E+00  A4 = −3.35320E−07  A6= −5.17749E−08  A8 = 8.91765E−10 A10 = −5.73216E−12 Surface number: 25 κ = 1.00000E+00  A4 = 1.10647E−05  A6 = 2.12638E−08  A8 = −1.45298E−10A10 = 1.80548E−13 Surface number: 29  κ = 1.00000E+00  A4 = 9.54720E−06 A6 = −3.28939E−08  A8 = 9.31216E−11 A10 = −9.94866E−14 Surface number:30  κ = 1.00000E+00  A4 = 1.57892E−05  A6 = −4.68421E−08  A8 =1.10504E−10 A10 = −1.06766E−13 [Variable Distance Data] W M T W M TInfinity Infinity Infinity Close point Close point Close point d0 ∞ ∞ ∞120.16 124.28 118.11 β — — — −0.1141 −0.1719 −0.2434 f 16.48 25.21 33.95— — — d8 26.758 8.756 0.500 31.009 13.089 5.283 d13 7.532 7.532 7.5323.280 3.198 2.749 d17 2.000 5.495 7.430 2.000 5.495 7.430 d22 6.9303.434 1.500 6.930 3.434 1.500 d28 3.850 17.737 32.161 3.850 17.73732.161 BF 18.060 18.054 18.063 18.135 18.223 18.401 [ConditionalExpression Correspondence Values] (1) (−f3)/fw = 4.248 (2) |m34|/fw =0.329 (3) f5/(−f1) = 3.244 (4) |m12|/fw = 1.593 (5) f5/f4 = 0.843 (6)f4/f2 = 2.556 (7) (r1 + r2)/(r1 − r2) = 1.963

FIG. 22 shows graphs illustrating various aberrations of the zoom lensaccording to Example 6 upon focusing on an object at infinity, whereinparts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 23 shows graphs illustrating various aberrations of the zoom lensaccording to Example 6 upon focusing on an object at a close point,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 24 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 6 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 6 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

Example 7

FIG. 25 is a cross-sectional view of a zoom lens according to Example 7,wherein parts (a), (b), and (d) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

Arrows under each lens group in FIG. 25(a) indicate the movingdirections of each lens group upon varying magnification from thewide-angle end state to the intermediate focal length state. Arrowsunder each lens group in FIG. 25(b) indicate the moving directions ofeach lens group upon varying magnification from the intermediate focallength state to the telephoto end state.

As illustrated in FIG. 25(a), a zoom lens according to this example isconstituted by, in order from an object along an optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, a third lens group G3 having anegative refractive power, a fourth lens group G4 having a positiverefractive power, and a fifth lens group G5 having a positive refractivepower.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a biconcavelens L13, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces. The negative meniscus lens L12 isan aspherical lens of which the image-side lens surface is an asphericalsurface.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a second F lens group G2F having a positiverefractive power and a second R lens group G2R having a positiverefractive power.

The second F lens group G2F is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side and a biconcave lens L23. The biconvex lens L21is an aspherical lens of which the object-side lens surface is anaspherical surface.

The second R lens group G2R is constituted by, in order from the objectalong the optical axis, a cemented lens including a negative meniscuslens L24 having a convex surface oriented toward the object side, abiconvex lens L25, and a negative meniscus lens L26 having a concavesurface oriented toward the object side. The negative meniscus lens L24is an aspherical lens of which the object-side lens surface is anaspherical surface.

The third lens group G3 is constituted by, in order from the objectalong the optical axis, an aperture stop S, a cemented lens including abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side, and a flare-cut diaphragm FS.

The fourth lens group G4 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L41and a negative meniscus lens L42 having a concave surface orientedtoward the object side and a cemented lens including a negative meniscuslens L43 having a convex surface oriented toward the object side and apositive meniscus lens L44 having a convex surface oriented toward theobject side. The negative meniscus lens L42 is an aspherical lens ofwhich the image-side lens surface is an aspherical surface.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, and thefourth lens group G4 move along the optical axis in relation to theimage plane I such that the distance between the first and second lensgroups G1 and G2 decreases, the distance between the second and thirdlens groups G2 and G3 increases, the distance between the third andfourth lens groups G3 and G4 decreases, and the distance between thefourth and fifth lens groups G4 and G5 increases. Specifically, when thezoom lens performs varying magnification, the first lens group G1 ismoved toward the image plane I and is then moved toward the object side,the second and fourth lens groups G2 and G4 are moved integrally towardthe object side, the third lens group G3 is moved toward the objectside, and the fifth lens group G5 is immovable in relation to the imageplane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved together with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thesecond F lens group G2F toward the image plane I.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the cemented lens of the fourth lens group G4 including thebiconvex lens L41 and the negative meniscus lens L42 having a concavesurface oriented toward the object side in such a direction as toinclude a component in the direction orthogonal to the optical axis as avibration-reduction lens group.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 0.84 and the focal lengthis 16.48 (mm) (see Table 8 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.81°is 0.28 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 1.12 and the focal length is25.21 (mm) (see Table 8 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.26 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 1.39 and the focal length is 33.94 (mm) (seeTable 8 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.24 (mm).

Table 7 below illustrates the specification values of the zoom lensaccording to Example 7.

TABLE 7 Example 7 [Overall Specification] W M T f 16.48 25.21 33.94 FNO4.00 4.00 4.00 ω 54.1 40.0 31.8 Y 21.64 21.64 21.64 TL 156.155 150.831154.903 BF 18.066 18.053 18.060 [Surface Data] Surface number r d nd νdObject plane ∞  *1) 193.58721 2.000 1.82080 42.7  *2) 20.02145 6.905  3)90.01817 2.000 1.90043 37.4  *4) 27.89307 9.933  5) −41.38646 2.0001.49782 82.6  6) 388.04959 0.150  7) 63.78120 5.582 2.00100 29.1  8)−140.47475 (Variable)  *9) 34.11887 7.683 1.58313 59.4  10) −23.190931.500 1.65844 50.8  11) −43.34847 0.150  12) −133.64479 1.500 1.5174252.2  13) 43.43678 (Variable) *14) 43.27875 1.500 1.79504 28.7  15)26.75575 9.166 1.48749 70.3  16) −21.47016 1.500 1.68893 31.2  17)−29.83058 (Variable)  18) (Diaphragm) ∞ 4.000  19) −117.95737 1.5001.74400 44.8  20) 20.54277 3.285 1.80244 25.6  21) 54.89929 1.000  22)(FS) ∞ (Variable)  23) 32.72024 9.645 1.49782 82.6  24) −23.86366 1.5001.88202 37.2 *25) −34.86203 0.150  26) 69.62430 1.500 1.90043 37.4  27)18.05008 9.020 1.49782 82.6  28) 104.94552 (Variable) *29) −135.000004.710 1.77250 49.5 *30) −48.92153 (BF) Image plane ∞ [Lens Group Data]Starting surface Focal distance G1  1 −23.31 G2  9 35.87 G3 18 −54.84 G423 83.18 G5 29 97.01 [Aspheric Data]   Surface number: 1  κ =2.00000E+00  A4 = 7.90218E−06  A6 = −3.67128E−09  A8 = 1.11425E−12 A10 =−3.22487E−16 Surface number: 2  κ = 9.06000E−02  A4 = −1.10492E−05  A6 =4.18700E−08  A8 = −2.82799E−11 A10 = 8.48422E−14 Surface number: 4  κ =1.00000E+00  A4 = 2.06544E−05  A6 = 1.14896E−09  A8 = −9.32488E−11 A10 =1.06908E−13 Surface number: 9  κ = 1.00000E+00  A4 = −5.99537E−06  A6 =−8.64207E−09  A8 = 0.00000E+00 A10 = 0.00000E+00 Surface number: 14  κ =1.00000E+00  A4 = −5.24252E−06  A6 = 3.78138E−09  A8 = −1.26184E−11 A10= −1.01048E−14 Surface number: 25  κ = 1.00000E+00  A4 = 5.70046E−06  A6= −3.54520E−09  A8 = 1.13461E−11 A10 = −1.29870E−13 Surface number: 29 κ = 1.00000E+00  A4 = 2.14047E−06  A6 = −2.58918E−09  A8 = 4.54444E−11A10 = −7.04486E−14 Surface number: 30  κ = 1.00000E+00  A4 = 5.01764E−06 A6 = −9.55833E−09  A8 = 5.69307E−11 A10 = −7.79067E−14 [VariableDistance Data] W M T W M T Infinity Infinity Infinity Close point Closepoint Close point d0 ∞ ∞ ∞ 116.21 121.52 117.46 β — — — −0.1183 −0.1768−0.2470 f 16.48 25.21 33.94 — — — d8 27.092 8.876 0.500 30.852 12.6224.589 d13 7.348 7.348 7.348 3.588 3.603 3.259 d17 2.000 6.293 9.7402.000 6.293 9.740 d22 9.240 4.947 1.500 9.240 4.947 1.500 d28 4.52817.433 29.874 4.528 17.433 29.874 BF 18.066 18.053 18.060 18.146 18.23218.406 [Conditional Expression Correspondence Values] (1) (−f3)/fw =3.329 (2) |m34|/fw = 0.470 (3) f5/(−f1) = 4.162 (4) |m12|/fw = 1.614 (5)f5/f4 = 1.166 (6) f4/f2 = 2.319 (7) (r1 + r2)/(r1 − r2) = 2.137

FIG. 26 shows graphs illustrating various aberrations of the zoom lensaccording to Example 7 upon focusing on an object at infinity, whereinparts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 27 shows graphs illustrating various aberrations of the zoom lensaccording to Example 7 upon focusing on an object at a close point,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 28 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 7 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 7 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

Example 8

FIG. 29 is a cross-sectional view of a zoom lens according to Example 8,wherein parts (a), (b), and (d) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

Arrows under each lens group in FIG. 29(a) indicate the movingdirections of each lens group upon varying magnification from thewide-angle end state to the intermediate focal length state. Arrowsunder each lens group in FIG. 29(b) indicate the moving directions ofeach lens group upon varying magnification from the intermediate focallength state to the telephoto end state.

As illustrated in FIG. 29(a), a zoom lens according to this example isconstituted by, in order from an object along an optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, an aperture stop S, a third lensgroup G3 having a negative refractive power, a fourth lens group G4having a positive refractive power, and a fifth lens group G5 having apositive refractive power.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a biconcavelens L13, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces. The negative meniscus lens L12 isan aspherical lens of which the image-side lens surface is an asphericalsurface.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side, a biconcave lens L23, and a cemented lensincluding a negative meniscus lens L24 having a convex surface orientedtoward the object side, a biconvex lens L25, and a negative meniscuslens L26 having a concave surface oriented toward the object side. Thebiconvex lens L21 is an aspherical lens of which the object-side lenssurface is an aspherical surface. The negative meniscus lens L24 is anaspherical lens of which the object-side lens surface is an asphericalsurface.

The third lens group G3 is constituted by a cemented lens including abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side.

The fourth lens group G4 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L41and a negative meniscus lens L42 having a concave surface orientedtoward the object side and a cemented lens including a negative meniscuslens L43 having a convex surface oriented toward the object side and apositive meniscus lens L44 having a convex surface oriented toward theobject side. The negative meniscus lens L42 is an aspherical lens ofwhich the image-side lens surface is an aspherical surface.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, the fourthlens group G4, and the fifth lens group G5 move along the optical axisin relation to the image plane I such that the distance between thefirst and second lens groups G1 and G2 decreases, the distance betweenthe second and third lens groups G2 and G3 increases, the distancebetween the third and fourth lens groups G3 and G4 decreases, and thedistance between the fourth and fifth lens groups G4 and G5 increases.Specifically, when the zoom lens performs varying magnification, thefirst lens group G1 is moved toward the image plane I and is then movedtoward the object side, the second and fourth lens groups G2 and G4 aremoved integrally toward the object side, the third lens group G3 ismoved toward the object side, and the fifth lens group G5 is movedtoward the image plane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved integrally with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thethird lens group G3 toward the image plane I.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the cemented lens of the second lens group G2 including thenegative meniscus lens L24 having a convex surface oriented toward theobject side, the biconvex lens L25, and the negative meniscus lens L26having a concave surface oriented toward the object side in such adirection as to include a component in the direction orthogonal to theoptical axis as a vibration-reduction lens group.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 1.06 and the focal lengthis 16.48 (mm) (see Table 9 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.81°is 0.22 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 1.32 and the focal length is25.21 (mm) (see Table 9 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.22 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 1.64 and the focal length is 33.95 (mm) (seeTable 9 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.20 (mm).

Table 8 below illustrates the specification values of the zoom lensaccording to Example 8.

TABLE 8 Example 8 [Overall Specification] W M T f 16.48 25.21 33.95 FNO4.00 4.00 4.00 ω 54.0 39.4 31.8 Y 21.64 21.64 21.64 TL 162.365 154.491161.772 BF 23.901 22.523 18.067 [Surface Data] Surface number r d nd νdObject plane ∞  *1) 206.62948 2.000 1.82080 42.7  *2) 22.78595 5.394  3)79.60930 2.000 1.90043 37.4  *4) 28.62293 12.227  5) −36.79633 2.0001.49782 82.6  6) 138.93269 0.150  7) 59.13309 5.614 2.00100 29.1  8)−157.09491 (Variable)  *9) 78.52593 8.740 1.58313 59.4  10) −18.336221.500 1.65844 50.8  11) −31.62205 0.320  12) −53.95141 1.500 1.5174252.2  13) 1642.72200 5.830 *14) 56.55132 1.500 1.79504 28.7  15)30.04155 10.867 1.48749 70.3  16) −20.18962 1.500 1.68893 31.2  17)−26.35355 (Variable)  18) (Diaphragm) ∞ (Variable)  19) −107.45547 1.5001.74400 44.8  20) 19.22984 3.482 1.80244 25.6  21) 51.40293 (Variable) 22) 43.71137 7.983 1.49782 82.6  23) −23.27350 1.500 1.88202 37.2 *24)−31.21137 0.150  25) 71.81959 1.500 1.90043 37.4  26) 18.76437 8.4731.49782 82.6  27) 145.88740 (Variable) *28) −135.00000 4.550 1.7725049.5 *29) −52.15640 (BF) Image plane ∞ [Lens Group Data] Startingsurface Focal distance G1  1 −24.38 G2  9 34.96 G3 19 −50.79 G4 22 84.06G5 28 107.45 [Aspheric Data]   Surface number: 1  κ = 0.00000E+00  A4 =7.49847E−06  A6 = −4.72101E−09  A8 = 1.34426E−12 A10 = 7.77327E−16Surface number: 2  κ = 1.11000E−02  A4 = −2.39129E−05  A6 = 4.34446E−08 A8 = −4.32137E−11 A10 = 3.44930E−14 Surface number: 4  κ = 1.00000E+00 A4 = 3.53137E−05  A6 = 6.78430E−09  A8 = −4.22471E−11 A10 = 4.95919E−14Surface number: 9  κ = 1.00000E+00  A4 = −4.89433E−06  A6 = −9.35308E−09 A8 = 0.00000E+00 A10 = 0.00000E+00 Surface number: 14  κ = 1.00000E+00 A4 = −6.54457E−06  A6 = 5.07738E−09  A8 = −5.16352E−11 A10 =2.09233E−13 Surface number: 24  κ = 1.00000E+00  A4 = 2.08758E−06  A6 =1.15759E−08  A8 = −7.29250E−11 A10 = 1.18188E−13 Surface number: 28  κ =1.00000E+00  A4 = 2.27203E−06  A6 = 1.20614E−09  A8 = 2.01555E−11 A10 =−4.02390E−14 Surface number: 29  κ = 1.00000E+00  A4 = 6.10900E−06  A6 =−4.88513E−09  A8 = 2.18415E−11 A10 = −3.91619E−14 [Variable DistanceData] W M T W M T Infinity Infinity Infinity Close point Close pointClose point d0 ∞ ∞ ∞ 110.00 117.87 110.60 β — — — −0.1310 −0.1947−0.2863 f 16.48 25.21 33.95 — — — d8 27.288 7.805 0.500 27.288 7.8050.500 d17 2.000 7.042 8.304 2.000 7.042 8.304 d18 4.000 4.000 4.0005.664 7.386 9.288 d21 12.429 7.386 6.125 10.765 4.000 0.837 d27 2.46815.455 34.496 2.468 15.455 34.496 BF 23.901 22.523 18.067 23.999 22.74018.534 [Conditional Expression Correspondence Values] (1) (−f3)/fw =3.082 (2) |m34|/fw = 0.383 (3) f5/(−f1) = 4.408 (4) |m12|/fw = 1.626 (5)f5/f4 = 1.278 (6) f4/f2 = 2.405 (7) (r1 + r2)/(r1 − r2) = 2.259

FIG. 30 shows graphs illustrating various aberrations of the zoom lensaccording to Example 8 upon focusing on an object at infinity in,wherein parts (a), (b), and (d) are the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 31 shows graphs illustrating various aberrations of the zoom lensaccording to Example 8 upon focusing on an object at a close point,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 32 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 8 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 8 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

Example 9

FIG. 33 is a cross-sectional view of a zoom lens according to Example 9,wherein parts (a), (b), and (d) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

Arrows under each lens group in FIG. 33(a) indicate the movingdirections of each lens group upon varying magnification from thewide-angle end state to the intermediate focal length state. Arrowsunder each lens group in FIG. 33(b) indicate the moving directions ofeach lens group upon varying magnification from the intermediate focallength state to the telephoto end state.

As illustrated in FIG. 33(a), a zoom lens according to this example isconstituted by, in order from an object along an optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, a third lens group G3 having anegative refractive power, a fourth lens group G4 having a positiverefractive power, and a fifth lens group G5 having a positive refractivepower.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a biconcavelens L13, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces. The negative meniscus lens L12 isan aspherical lens of which the image-side lens surface is an asphericalsurface.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side, a biconcave lens L23, and a cemented lensincluding a negative meniscus lens L24 having a convex surface orientedtoward the object side, a biconvex lens L25, and a negative meniscuslens L26 having a concave surface oriented toward the object side. Thebiconvex lens L21 is an aspherical lens of which the object-side lenssurface is an aspherical surface. The negative meniscus lens L24 is anaspherical lens of which the object-side lens surface is an asphericalsurface.

The third lens group G3 is constituted by, in order from the objectalong the optical axis, an aperture stop S and a cemented lens includinga biconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side.

The fourth lens group G4 is constituted by, in order from the objectalong the optical axis, a fourth F lens group G4F having a positiverefractive power and a fourth R lens group G4R having a negativerefractive power.

The fourth F lens group G4F is constituted by a cemented lens includinga biconvex lens L41 and a negative meniscus lens L42 having a concavesurface oriented toward the object side. The negative meniscus lens L42is an aspherical lens of which the image-side lens surface is anaspherical surface.

The fourth R lens group G4R is constituted by a cemented lens includinga negative meniscus lens L43 having a convex surface oriented toward theobject side and a positive meniscus lens L44 having a convex surfaceoriented toward the object side.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, the fourthlens group G4, and the fifth lens group G5 move along the optical axisin relation to the image plane I such that the distance between thefirst and second lens groups G1 and G2 decreases, the distance betweenthe second and third lens groups G2 and G3 increases, the distancebetween the third and fourth lens groups G3 and G4 decreases, and thedistance between the fourth and fifth lens groups G4 and G5 increases.Specifically, when the zoom lens performs varying magnification, thefirst lens group G1 is moved toward the image plane I and is then movedtoward the object side, the second and fourth lens groups G2 and G4 aremoved integrally toward the object side, the third lens group G3 ismoved toward the object side, and the fifth lens group G5 is movedtoward the object side and is then moved toward the image plane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved together with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thefourth F lens group G4F toward the object side.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the cemented lens of the second lens group G2 including thenegative meniscus lens L24 having a convex surface oriented toward theobject side, the biconvex lens L25, and the negative meniscus lens L26having a concave surface oriented toward the object side in such adirection as to include a component in the direction orthogonal to theoptical axis as a vibration-reduction lens group.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 1.01 and the focal lengthis 16.48 (mm) (see Table 10 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.81°is 0.23 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 1.28 and the focal length is25.22 (mm) (see Table 10 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.23 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 1.58 and the focal length is 33.95 (mm) (seeTable 10 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.21 (mm).

Table 9 below illustrates the specification values of the zoom lensaccording to Example 9.

TABLE 9 Example 9 [Overall Specification] W M T f 16.48 25.22 33.95 FNO4.00 4.00 4.00 ω 54.0 39.5 31.8 Y 21.64 21.64 21.64 TL 157.040 150.577158.386 BF 19.612 20.204 18.091 [Surface Data] Surface number r d nd νdObject plane ∞  *1) 748.12416 2.000 1.82080 42.7  *2) 24.27981 6.249  3)82.72688 2.000 1.90043 37.4  *4) 29.19843 11.941  5) −38.35396 2.0001.49782 82.6  6) 123.88139 0.150  7) 58.33566 5.662 2.00100 29.1  8)−157.62198 (Variable)  *9) 53.58324 6.922 1.58313 59.4  10) −22.479031.500 1.65454 55.0  11) −43.36840 0.150  12) −111.21206 1.500 1.5174252.2  13) 108.52980 7.626 *14) 45.76109 1.500 1.82227 25.8  15) 27.9457510.712 1.48749 70.3  16) −23.08227 1.500 1.68893 31.2  17) −31.09319(Variable)  18) (Diaphragm) ∞ 4.000  19) −95.69123 1.500 1.74400 44.8 20) 28.24642 3.135 1.80244 25.6  21) 114.16154 (Variable)  22) 45.668716.767 1.49782 82.6  23) −24.10121 1.500 1.88202 37.2 *24) −36.88706(Variable)  25) 51.43628 1.500 1.90043 37.4  26) 17.97428 6.908 1.4978282.6  27) 53.78862 (Variable) *28) −135.00000 4.998 1.77250 49.5 *29)−46.24500 (BF) Image plane ∞ [Lens Group Data] Starting surface Focaldistance G1  1 −24.13 G2  9 36.72 G3 18 −77.89 G4 22 151.54 G5 28 88.87[Aspheric Data]   Surface number: 1  κ = 0.00000E+00  A4 = 9.52593E−06 A6 = −6.95106E−09  A8 = 1.81770E−12 A10 = 4.34677E−16 Surface number: 2 κ = 1.04000E−01  A4 = −2.28424E−05  A6 = 3.85220E−08  A8 = −4.02855E−11A10 = 2.50646E−14 Surface number: 4  κ = 1.00000E+00  A4 = 3.45313E−05 A6 = 2.43926E−08  A8 = −5.26585E−11 A10 = −1.44105E−14 Surface number:9  κ = 1.00000E+00  A4 = −3.39462E−06  A6 = −4.52751E−09  A8 =0.00000E+00 A10 = 0.00000E+00 Surface number: 14  κ = 1.00000E+00  A4 =−3.99540E−06  A6 = 6.90128E−09  A8 = −7.15162E−11 A10 = 2.30252E−13Surface number: 24  κ = 1.00000E+00  A4 = 2.95224E−06  A6 = 6.31531E−09 A8 = −6.95778E−11 A10 = 9.58472E−14 Surface number: 28  κ = 1.00000E+00 A4 = 3.07452E−06  A6 = 6.73524E−10  A8 = 1.35472E−11 A10 = −3.33968E−14Surface number: 29  κ = 1.00000E+00  A4 = 7.09095E−06  A6 = −3.53806E−09 A8 = 1.19967E−11 A10 = −2.88780E−14 [Variable Distance Data] W M T W MT Infinity Infinity Infinity Close point Close point Close point d0 ∞ ∞∞ 115.33 121.81 114.01 β — — — −0.1237 −0.1846 −0.2688 f 16.48 25.2233.95 — — — d8 26.754 7.684 0.500 26.754 7.684 0.500 d17 2.000 7.9009.425 2.000 7.900 9.425 d21 11.786 5.887 4.361 10.002 2.909 0.209 d240.150 0.150 0.150 1.935 3.128 4.301 d27 5.019 17.035 34.140 5.019 17.03534.140 BF 19.612 20.204 18.091 19.700 20.399 18.504 [ConditionalExpression Correspondence Values] (1) (−f3)/fw = 4.726 (2) |m34|/fw =0.451 (3) f5/(−f1) = 3.682 (4) |m12|/fw = 1.593 (5) f5/f4 = 0.586 (6)f4/f2 = 4.127 (7) (r1 + r2)/(r1 − r2) = 2.042

FIG. 34 shows graphs illustrating various aberrations of the zoom lensaccording to Example 9 upon focusing on an object at infinity, whereinparts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 35 shows graphs illustrating various aberrations of the zoom lensaccording to Example 9 upon focusing on an object at a close point,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 36 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 9 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 9 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

Example 10

FIG. 37 is a cross-sectional view of a zoom lens according to Example10, wherein parts (a), (b), and (d) are in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

Arrows under each lens group in FIG. 37(a) indicate the movingdirections of each lens group upon varying magnification from thewide-angle end state to the intermediate focal length state. Arrowsunder each lens group in FIG. 37(b) indicate the moving directions ofeach lens group upon varying magnification from the intermediate focallength state to the telephoto end state.

As illustrated in FIG. 37(a), a zoom lens according to this example isconstituted by, in order from an object along an optical axis, a firstlens group G1 having a negative refractive power, a second lens group G2having a positive refractive power, a third lens group G3 having anegative refractive power, a fourth lens group G4 having a positiverefractive power, and a fifth lens group G5 having a positive refractivepower.

The first lens group G1 is constituted by, in order from the objectalong the optical axis, a negative meniscus lens L11 having a convexsurface oriented toward the object side, a negative meniscus lens L12having a convex surface oriented toward the object side, a biconcavelens L13, and a biconvex lens L14. The negative meniscus lens L11 is anaspherical lens of which the object-side lens surface and the image-sidelens surface are aspherical surfaces. The negative meniscus lens L12 isan aspherical lens of which the image-side lens surface is an asphericalsurface.

The second lens group G2 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L21and a negative meniscus lens L22 having a concave surface orientedtoward the object side, a biconcave lens L23, and a cemented lensincluding a negative meniscus lens L24 having a convex surface orientedtoward the object side, a biconvex lens L25, and a negative meniscuslens L26 having a concave surface oriented toward the object side. Thebiconvex lens L21 is an aspherical lens of which the object-side lenssurface is an aspherical surface. The negative meniscus lens L24 is anaspherical lens of which the object-side lens surface is an asphericalsurface.

The third lens group G3 is constituted by, in order from the objectalong the optical axis, an aperture stop S, a cemented lens including abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side, and a flare-cut diaphragm FS.

The fourth lens group G4 is constituted by, in order from the objectalong the optical axis, a cemented lens including a biconvex lens L41and a negative meniscus lens L42 having a concave surface orientedtoward the object side and a cemented lens including a negative meniscuslens L43 having a convex surface oriented toward the object side and abiconvex lens L44. The negative meniscus lens L42 is an aspherical lensof which the image-side lens surface is an aspherical surface.

The fifth lens group G5 is constituted by a positive meniscus lens L51having a concave surface oriented toward the object side. The positivemeniscus lens L51 is an aspherical lens of which the object-side lenssurface and the image-side lens surface are aspherical surfaces.

An image sensor (not illustrated) configured as a CCD, CMOS, or the likeis disposed at the image plane I.

In the zoom lens according to this example having the above-describedconfiguration, when the zoom lens performs varying magnification fromthe wide-angle end state to the telephoto end state, the first lensgroup G1, the second lens group G2, the third lens group G3, the fourthlens group G4, and the fifth lens group G5 move along the optical axisin relation to the image plane I such that the distance between thefirst and second lens groups G1 and G2 decreases, the distance betweenthe second and third lens groups G2 and G3 increases, the distancebetween the third and fourth lens groups G3 and G4 decreases, and thedistance between the fourth and fifth lens groups G4 and G5 increases.Specifically, when the zoom lens performs varying magnification, thefirst lens group G1 is moved toward the image plane I and is then movedtoward the object side, the second and fourth lens groups G2 and G4 aremoved integrally toward the object side, the third lens group G3 ismoved toward the object side, and the fifth lens group G5 is movedtoward the object side and is then moved toward the image plane I.

The aperture stop S is disposed between the second and third lens groupsG2 and G3 and is moved together with the third lens group G3 uponvarying magnification from the wide-angle end state to the telephoto endstate.

Moreover, the zoom lens according to this example performs focusing froman object at infinity to an object at a close distance by moving thefifth lens group G5 toward the object side.

Moreover, the zoom lens according to this example performs image planecorrection (that is, vibration reduction) when image blur occurs bymoving the cemented lens of the second lens group G2 including thenegative meniscus lens L24 having a convex surface oriented toward theobject side, the biconvex lens L25, and the negative meniscus lens L26having a concave surface oriented toward the object side in such adirection as to include a component in the direction orthogonal to theoptical axis as a vibration-reduction lens group.

Here, when the focal length of an entire system of the zoom lensaccording to this example is f and the ratio of a moving distance of animage on the image plane I with respect to a moving distance of thevibration-reduction lens group during blur correction is K, in order tocorrect rotation blur of angle θ, the vibration-reduction lens group maybe shifted in the direction orthogonal to the optical axis by (f·tanθ)/K.

In the zoom lens according to this example, in the wide-angle end state,since the vibration reduction coefficient K is 0.97 and the focal lengthis 16.48 (mm) (see Table 11 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.81°is 0.24 (mm). Moreover, in the intermediate focal length state, sincethe vibration reduction coefficient K is 1.19 and the focal length is25.21 (mm) (see Table 11 below), the moving distance of thevibration-reduction lens group for correcting the rotation blur of 0.66°is 0.24 (mm). Moreover, in the telephoto end state, since the vibrationreduction coefficient K is 1.43 and the focal length is 33.94 (mm) (seeTable 11 below), the moving distance of the vibration-reduction lensgroup for correcting the rotation blur of 0.57° is 0.23 (mm).

Table 10 below illustrates the specification values of the zoom lensaccording to Example 10.

TABLE 10 Example 10 [Overall Specification] W M T f 16.48 25.21 33.94FNO 4.00 4.00 4.00 ω 54.1 40.4 32.8 Y 21.64 21.64 21.64 TL 162.327153.706 157.417 BF 18.026 19.051 18.015 [Surface Data] Surface number rd nd νd Object plane ∞  *1) 132.59820 2.000 1.82080 42.7  *2) 19.322717.442  3) 160.87743 2.000 1.90043 37.4  *4) 32.91214 9.741  5) −38.074642.000 1.49782 82.6  6) 561.24096 0.150  7) 73.09225 5.033 2.00100 29.1 8) −129.44599 (Variable)  *9) 40.27118 7.618 1.58313 59.4  10)−22.79658 1.500 1.65160 58.6  11) −37.12857 2.061  12) −39.17300 1.5001.51742 52.2  13) 1874.52540 1.776 *14) 51.35062 1.500 1.79504 28.7  15)28.77558 8.221 1.48749 70.3  16) −23.13956 1.500 1.68893 31.2  17)−31.27181 (Variable)  18) (Diaphragm) ∞ 4.000  19) −105.52859 1.5001.74400 44.8  20) 25.92479 2.859 1.80244 25.6  21) 69.72964 1.000  22)(FS) ∞ (Variable)  23) 65.71858 10.859 1.49782 82.6  24) −19.28535 1.5001.88202 37.2 *25) −31.97958 1.150  26) 89.97758 1.500 1.90043 37.4  27)24.75006 11.838 1.49782 82.6  28) −103.72759 (Variable) *29) −135.000004.892 1.77250 49.5 *30) −59.90604 (BF) Image plane ∞ [Lens Group Data]Starting surface Focal distance G1  1 −21.74 G2  9 34.29 G3 18 −60.80 G423 73.88 G5 29 135.56 [Aspheric Data]   Surface number: 1  κ =0.00000E+00  A4 = 1.16094E−05  A6 = −9.06420E−09  A8 = 2.81639E−12 A10 =2.24774E−15 Surface number: 2  κ = 1.30300E−01  A4 = −1.18813E−05  A6 =5.68936E−08  A8 = −9.29931E−11 A10 = 2.59824E−14 Surface number: 4  κ =1.00000E+00  A4 = 2.67754E−05  A6 = −6.40784E−09  A8 = −5.02628E−11 A10= 2.60885E−13 Surface number: 9  κ = 1.00000E+00  A4 = −2.85903E−06  A6= −6.88788E−09  A8 = 0.00000E+00 A10 = 0.00000E+00 Surface number: 14  κ= 1.00000E+00  A4 = −4.52862E−06  A6 = 3.83779E−09  A8 = −2.25240E−11A10 = 7.59629E−14 Surface number: 25  κ = 1.00000E+00  A4 = 4.32494E−06 A6 = 5.82097E−09  A8 = −4.56687E−11 A10 = 3.78592E−14 Surface number:29  κ = 1.00000E+00  A4 = 9.68518E−06  A6 = −2.01079E−08  A8 =1.31643E−11 A10 = −2.09414E−15 Surface number: 30  κ = 1.00000E+00  A4 =8.93441E−06  A6 = −2.66479E−08  A8 = 2.35900E−11 A10 = −9.65459E−15[Variable Distance Data] W M T W M T Infinity Infinity Infinity Closepoint Close point Close point d0 ∞ ∞ ∞ 230.00 238.63 234.90 β — — —−0.0651 −0.0951 −0.1271 f 16.48 25.21 33.94 — — — d8 29.064 8.952 0.50029.064 8.952 0.500 d17 2.000 9.683 15.225 2.000 9.683 15.225 d22 14.7257.042 1.500 14.725 7.042 1.500 d28 4.371 14.839 28.037 0.147 6.66714.415 BF 18.026 19.051 18.015 22.275 22.275 31.731 [ConditionalExpression Correspondence Values] (1) (−f3)/fw = 3.690 (2) |m34|/fw =0.803 (3) f5/(−f1) = 6.234 (4) |m12|/fw = 1.734 (5) f5/f4 = 1.835 (6)f4/f2 = 2.155 (7) (r1 + r2)/(r1 − r2) = 2.596

FIG. 38 shows graphs illustrating various aberrations of the zoom lensaccording to Example 10 upon focusing on an object at infinity, whereinparts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 39 shows graphs illustrating various aberrations of the zoom lensaccording to Example 10 upon focusing on an object at a close point in,wherein parts (a), (b), and (d) are the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

FIG. 40 shows graphs illustrating meridional lateral aberrations of thezoom lens according to Example 10 when vibration reduction is performed,wherein parts (a), (b), and (d) are in the wide-angle end state, theintermediate focal length state, and the telephoto end state,respectively.

It can be understood from the respective aberration diagrams that thezoom lens according to Example 10 can satisfactorily correct variousaberrations in states ranging from the wide-angle end state to thetelephoto end state and has an excellent optical performance uponvibration reduction.

As described above, according to the respective examples, it is possibleto implement a zoom lens having an F-number for brightness and anexcellent optical performance. Particularly, it is possible to implementa zoom lens of which the variable magnification ratio (variable powerratio) is between approximately 1.5 and 2.5 and which has a brightnessof an F-number of approximately 2.8 to 4.0 and a wide angle of view.Moreover, it is possible to decrease the size of a vibration-reductionlens group and to achieve an excellent optical performance uponvibration reduction. According to the respective examples, it ispossible to implement a zoom lens of which the half-angle of view (unit:degrees) in the wide-angle end state is in the range of 39<ωW<57 (morepreferably, 42<ωW<57).

Moreover, it is preferable that the half-angle of view (unit: degrees)in the wide-angle end state of the zoom lens be in the range of 39<ωW<57(more specifically, 42<ωW<57). Moreover, it is preferable that theF-number of the zoom lens be approximately constant when performingvarying magnification from the wide-angle end state to the telephoto endstate. Moreover, it is preferable that a motor for moving the focusinglens group of the zoom lens be a step motor. Furthermore, it ispreferable that the first lens group G1 move toward the image plane Iand then moves toward the object side when the zoom lens performsvarying magnification from the wide-angle end state to the telephoto endstate. Moreover, it is preferable that the fifth lens group G5 beimmovable in relation to the image plane I when the zoom lens performsvarying magnification from the wide-angle end state to the telephoto endstate. Moreover, it is preferable that the second and fourth lens groupsG2 and G4 move toward the object side along the same moving trajectoryby the same moving distance when the zoom lens performs varyingmagnification from the wide-angle end state to the telephoto end state.Moreover, the second and fourth lens groups G2 and G4 move toward theobject side but do not move toward the image side when the zoom lensperforms varying magnification from the wide-angle end state to thetelephoto end state. Moreover, the second, third, and fourth lens groupsG2, G3, and G4 may move in the same direction when the zoom lensperforms varying magnification. Moreover, the moving distance of thesecond and fourth lens groups G2 and G4 may be larger than the movingdistance of the third lens group G3 when the zoom lens performs varyingmagnification from the wide-angle end state to the telephoto end state.Moreover, the second and fourth lens groups G2 and G4 of the zoom lensmay be fixed to the same barrel member. Moreover, it is preferable thatthe distance between the first and second lens groups G1 and G2 change,the distance between the second and third lens groups G2 and G3 changes,the distance between the third and fourth lens groups G3 and G4 changes,and the distance between the fourth and fifth lens groups G4 and G5changes when the zoom lens performs varying magnification from thewide-angle end state to the telephoto end state.

The respective examples illustrate specific examples, but the presentinvention is not limited thereto. The following content can beappropriately employed within a range where the optical performance ofthe zoom lens is not diminished.

Although the numbered examples of a five-group configuration have beenillustrated as numbered examples of the zoom lens, the present inventioncan be applied to other group configurations such as a six-groupconfiguration or the like, for example. Specifically, a configuration inwhich a lens or a lens group is added to the side closest to the objectand a configuration in which a lens or a lens group is added to the sideclosest to the image may be employed. A lens group refers to a portionhaving at least one lens isolated by air space.

Moreover, in the zoom lens, a single lens group or plurality of lensgroups or a partial lens group may be moved in the optical axisdirection as a focusing lens group so as to perform focusing from anobject at infinity to an object at a close distance. This focusing lensgroup can be applied to autofocus and is also suitable for driving basedon an autofocus motor (for example, an ultrasonic motor or the like).Although it is particularly preferable that a portion of the second lensgroup G2 be used as the focusing lens group, a portion or the entireportion of the third and fifth lens groups G3 and G5 may be used as thefocusing lens group and the entire second lens group G2 may be used asthe focusing lens group.

In the zoom lens, an entire lens group or a partial lens group may bemoved so as to have a component in the direction orthogonal to theoptical axis or may be rotated (oscillated) in the direction includingthe optical axis so as to function as a vibration-reduction lens groupthat corrects image blur occurring due to camera shake or the like.Although it is particularly preferable that the entire third lens groupG3 be used as the vibration-reduction lens group, the entire portion ora portion of the fourth lens group G4 may be used as thevibration-reduction lens group and a portion of the third lens group maybe used as the vibration-reduction lens group.

Moreover, the lens surfaces of lenses that form the zoom lens may beformed as a spherical surface or a flat surface and may be formed as anaspherical surface. When a lens surface is a spherical surface or a flatsurface, it is possible to facilitate lens processing, assembly, andadjustment and to prevent deterioration of optical performance resultingfrom errors in the processing, assembly and adjustment. Moreover,deterioration of the rendering performance is little even when the imageplane is shifted. When a lens surface is an aspherical surface, theaspherical surface may be an aspherical surface obtained by grinding, aglass-molded aspherical surface obtained by molding glass into anaspherical surface, or a composite aspherical surface obtained byforming a resin on the surface of glass into an aspherical shape.Moreover, the lens surface may be a diffraction surface and may be arefractive index distributed lens (a GRIN lens) or a plastic lens.

In the zoom lens, although it is preferable that the aperture stop bedisposed between the second and third lens groups G2 and G3, the role ofthe aperture stop may be substituted by the frame of a lens withoutproviding a separate member as the aperture stop.

Moreover, the lens surfaces of lenses that form the zoom lens may becoated with an anti-reflection film which has high transmittance in awide wavelength region in order to decrease flare and ghosting andachieve satisfactory optical performance with high contrast.

Next, a camera having a zoom lens will be described with reference toFIG. 41 .

FIG. 41 is a schematic diagram illustrating a configuration of a camerahaving a zoom lens.

As illustrated in FIG. 41 , a camera 1 is a digital single-lens reflexcamera having the zoom lens according to Example 1 as an image capturinglens 2.

In the digital single-lens reflex camera 1 illustrated in FIG. 41 ,light from an object (a subject) (not illustrated) is collected by theimage capturing lens 2 and is imaged on an imaging plate 5 via a quickreturn mirror 3. Moreover, the light imaged on the imaging plate 5 isreflected a plurality of times in a pentagonal prism 7 and is guided toan eye lens 9. In this way, a photographer can observe an object(subject) image via the eye lens 9 as an erect image.

When a release button (not illustrated) is pressed by the photographer,the quick return mirror 4 moves out of an optical path and the object(subject) light collected by the image capturing lens 3 forms a subjectimage on an image sensor 11. In this way, light from an object is imagedby the image sensor 11 and is stored in a memory (not illustrated) as anobject image. In this way, the photographer can capture an image of theobject using the camera 1.

Here, the zoom lens according to Example 1 mounted on the camera 1 asthe image capturing lens 2 is a zoom lens having an F-number forbrightness and an excellent optical performance. Therefore, the camera 1is a camera having an excellent optical performance. A camera having thezoom lens according to any one of Examples 2 to 10 mounted thereon asthe image capturing lens 2 can provide the same effects as the camera 1.Moreover, the camera 1 may hold the image capturing lens 2 in adetachable manner and may be formed integrally with the image capturinglens 2. Moreover, the camera 1 may be a camera which does not have aquick return mirror and the like.

Next, a zoom lens manufacturing method will be described. FIGS. 42 and43 are diagrams illustrating an outline of a zoom lens manufacturingmethod.

In the example illustrated in FIG. 42 , a zoom lens manufacturing methodis a method for manufacturing a zoom lens including, in order from anobject along an optical axis, a first lens group having a negativerefractive power, a second lens group having a positive refractivepower, a third lens group having a negative refractive power, a fourthlens group, and a fifth lens group and includes step 10 as illustratedin FIG. 42 .

In step S10, when the zoom lens performs varying magnification, thedistance between the first and second lens groups changes, the distancebetween the second and third lens groups changes, the distance betweenthe third and fourth lens groups changes, the distance between thefourth and fifth lens groups changes, the second and fourth lens groupsmove along the same trajectory along the optical axis, and at least thethird lens group moves along the optical axis.

Alternatively, in the example illustrated in FIG. 43 , a zoom lensmanufacturing method is a method for manufacturing a zoom lensincluding, in order from an object along an optical axis, a first lensgroup having a negative refractive power, a second lens group having apositive refractive power, a third lens group having a negativerefractive power, a fourth lens group having a positive refractivepower, and a fifth lens group having a positive refractive power, andincludes step S1 as illustrated in FIG. 43 .

In step S1, when the zoom lens performs varying magnification, thesecond and fourth lens groups move by the same distance along theoptical axis, and at least the third lens group moves along the opticalaxis.

According to these zoom lens manufacturing methods, it is possible tomanufacture a zoom lens having an F-number for brightness and anexcellent optical performance. Particularly, it is possible tomanufacture a zoom lens of which the zoom ratio is between approximately1.5 and 2.5 and which has a brightness of an F-number of approximately2.8 to 4.0 and a wide angle of view.

EXPLANATION OF NUMERALS AND CHARACTERS

-   -   G1 First lens group    -   G2 Second lens group    -   G3 Third lens group    -   G4 Fourth lens group    -   G5 Fifth lens group    -   Gf Focusing lens group    -   S Aperture stop    -   FS Flare-cut diaphragm    -   I Image plane    -   1 Optical apparatus    -   2 Image capturing lens    -   3 Quick return mirror    -   5 Imaging plate    -   7 Pentagonal prism    -   9 Eye lens    -   11 Image sensor

The invention claimed is:
 1. A zoom lens comprising, in order from anobject along an optical axis: a first lens group having a negativerefractive power; a second lens group having a positive refractivepower; a third lens group having a negative refractive power; and afourth lens group having a positive refractive power, wherein when thezoom lens performs zooming, the first lens group moves along the opticalaxis, the distance between the first and second lens groups changes, thedistance between the second and third lens groups changes, and thedistance between the third and fourth lens groups changes, and thefollowing conditional expression is satisfied:0.300<|m12|/fw<5.000 where m12: a change in distance between the firstlens group and the second lens group along the optical axis upon zoomingfrom a wide-angle end state to a telephoto end state, fw: a focal lengthof the zoom lens in the wide-angle end state.
 2. The zoom lens accordingto claim 1, wherein the following conditional expression is satisfied:0.500<f4/f2<10.000 where f4: a focal length of the fourth lens group,f2: a focal length of the second lens group.
 3. The zoom lens accordingto claim 1, wherein the following conditional expression is satisfied:1.500<(−f3)/fw<10.000 where f3: a focal length of the third lens group.4. The zoom lens according to claim 1, wherein the following conditionalexpression is satisfied:0.050<|m34|/fw<1.500 where m34: a change in distance between the thirdlens group and the fourth lens group along the optical axis upon zoomingfrom the wide-angle end state to the telephoto end state.
 5. The zoomlens according to claim 1, wherein the second lens group moves along theoptical axis when the zoom lens performs zooming.
 6. The zoom lensaccording to claim 1, wherein the third lens group moves along theoptical axis when the zoom lens performs zooming.
 7. The zoom lensaccording to claim 1, wherein the fourth lens group moves along theoptical axis when the zoom lens performs zooming.
 8. The zoom lensaccording to claim 1, wherein in the first lens group, a negative lensis positioned closest to the object.
 9. The zoom lens according to claim1, wherein at least one lens of the third lens group is configured to bemovable so as to include a movement component in a direction orthogonalto the optical axis.
 10. The zoom lens according to claim 1, wherein thefirst lens group is constituted by, in order from the object along theoptical axis, a first negative lens, a second negative lens, a thirdnegative lens, and a positive lens.
 11. The zoom lens according to claim1, wherein the third lens group has a cemented lens including, in orderfrom the object along the optical axis, a negative lens and a positivelens.
 12. The zoom lens according to claim 1, wherein an aperture stopis provided between the second lens group and the third lens group. 13.An optical apparatus having the zoom lens of claim
 1. 14. A method formanufacturing a zoom lens, wherein the zoom lens includes, in order froman object along an optical axis: a first lens group having a negativerefractive power; a second lens group having a positive refractivepower; a third lens group having a negative refractive power; and afourth lens group having a positive refractive power, the methodcomprising: arranging the lens groups such that, when the zoom lensperforms zooming, the first lens group moves along the optical axis, thedistance between the first and second lens groups changes, the distancebetween the second and third lens groups changes, and the distancebetween the third and fourth lens groups changes; and satisfying thefollowing conditional expression:0.300<|m12|/fw<5.000 where m12: a change in distance between the firstlens group and the second lens group along the optical axis upon zoomingfrom a wide-angle end state to a telephoto end state, fw: a focal lengthof the zoom lens in the wide-angle end state.
 15. A zoom lenscomprising, in order from an object along an optical axis: a first lensgroup having a negative refractive power; a second lens group having apositive refractive power; a third lens group having a negativerefractive power; and a fourth lens group, wherein when the zoom lensperforms zooming, the first lens group moves along the optical axis, thedistance between the first and second lens groups changes, the distancebetween the second and third lens groups changes, the distance betweenthe third and fourth lens groups changes, the first lens group isconstituted by, in order from the object along the optical axis, a firstnegative lens, a second negative lens, a third negative lens, and apositive lens, and the following conditional expressions are satisfied:0.300<|m12|/fw<5.0001.500<(−f3)/fw<10.0000.050<|m34|/fw<1.500 where m12: a change in distance between the firstlens group and the second lens group along the optical axis upon zoomingfrom a wide-angle end state to a telephoto end state, fw: a focal lengthof the zoom lens in the wide-angle end state, f3: a focal length of thethird lens group, m34: a change in distance between the third lens groupand the fourth lens group along the optical axis upon zooming from thewide-angle end state to a telephoto end state.